Maintaining a high amount of Stability in your Cities sometimes can be fairly difficult, and it appears that a number of players have given feedback on that. It often requires spamming down a large number of Garrisons all over your lands, as well as rather constant vigilance over your Stability numbers. It can be argued that this can slow down how fast a player can progress, due to the fact that placing down Garrisons means the player cannot place down other Quarters that can contribute to the player’s economy. 

Stability also discourages players from picking Civics, since moving away from the center of the ideology will also remove the Stability bonuses. In addition, Stability as a mechanic makes Tall gameplay more difficult, because attaching Territories and having numerous Districts in a single City will cause substantial Stability hits. 

Enter AGRARIAN and BUILDER

I noted that during the Closed Beta, there seem to be a few people giving feedback on how weak the Agrarian and Builder passive abilities are, largely because they only give a burst of temporary Stability. I disagree with that assessment rather strongly - if you choose to use that ability to its fullest extent, it can be game-changing. 

Both the Agrarian and Builder Cultures have a special passive ability that adds Stability upon doing a particular action. For Agrarians, Cities will gain +5 Stability when they grow a Population. For Builders, they will gain +10 Stability upon finishing a District. 

Another thing to note is the fact that Cities will only lose -5 Stability per turn. If you happen to choose the ‘Forfeiture’ option on the Punishment Civic, that goes down to -4 Stability per turn. It doesn’t matter if the City has 95 Stability or 0, it’s always going to go down a set amount of Stability every single turn. This can be somewhat exploited, in that no matter how low Stability a City should have, you can always keep it at a high Stability via constantly feeding it small bursts of Stability. Such as the bursts of Stability from the Agrarian and Builder Affinities. 

So long as you grow a Population every turn, the Agrarian Affinity will give you exactly the amount of Stability needed to balance out any Stability you lost that turn. With Forfeiture, a City with “0 Stability” will actually be capable of gradually gaining Stability! Builder Affinities have a similar situation, where they need to build a single District once every two turns to balance out the Stability losses. 

Between Agrarian and Builder, Agrarian is probably the best Affinity for this particular strategy. Builders can run into a problem because District costs will constantly be increasing, so you may reach a point where the costs become too high for your Industry to complete it in two turns, after which your City will start to lose Stability. Agrarians have no such problem. If you reach the point where your Population eats too much Food and you can no longer grow in one turn, you can simply sacrifice some of them in Forced Labor. This means that as long as you’re using an Agrarian Culture and utilize their passive, then you can have zero Stability issues whatsoever. 

This offers a rather unique strategy. Simply keep on spamming Districts, keep on attaching Territories, and completely ignore the Stability maluses that those give you. Let the constant stream of Stability from your passives keep your Stability afloat. The fact that you are no longer required to build Garrisons and Commons Quarters to keep your Cities stable means you now have a huge amount of Industry opened up that can now be used to build other things. 

Given that you typically need to build a Garrison for every District to keep your Stability neutral, I’d say that this strategy can effectively double the number of Districts you can build, simply by eliminating Garrisons. Obviously, this isn’t always the case - Infrastructure, Units, and Wonders don’t cost any Stability, and as such don’t need a corresponding Garrison, and there are usually enough initial sources of Stability to cover your first few Districts. However, saying that this strategy is able to increase your effective Industry by 50% or so wouldn't be out of the question. 

And not only does this strategy free you up from building Garrisons and Commons Quarters, it also frees you up to take extreme positions on Ideologies. The +20 Stability from being in the center of Ideologies is extremely valuable for keeping your Stability high. But if you completely ignore Stability, there’s no need to stay in the center - you’ll be able to benefit from the higher yields of more extreme positions on Ideologies. 

Of course, this strategy has a drawback - you need to constantly be in either an Agrarian or Builder Culture. If you switch, you no longer have a way to increase your Stability, which is obviously going to be a problem. This is pretty much the only drawback, but it’s a major one. Being unable to get non-Agrarian/Builder Cultures will mean that you will have some difficulty obtaining a large amount of Influence, Money, or Science, which can slow down your progression. 

The reliance of needing to get one of two Affinities, of which there are is a total of three at most for a given Era, means that you’re nearly required to rush the next Era. In multiplayer, it wouldn’t be too difficult for other players to take the needed Affinities before you, especially if they figure out what your strategy is, and force you to Transcend instead of getting more abilities. 

However, a very notable side effect of this drawback is that nobody will want your Cities. If another player chooses to capture one of your Cities, or even annexes a Territory and attaches it, they’ll find that without your Affinity abilities, their City will have rather terrible Stability problems. This is likely going to be useful in Multiplayer, as having Cities with terrible Stability could possibly be more of a deterrent to warmongering players than having a large standing army and Garrisons everywhere. 

However, this single drawback will only impact you if you choose to go all-out. But as long as you use the strategy in moderation and end up fixing your Stability eventually, utilizing this Strategy can only benefit you. It can be useful when to use when you’re going to be dipping down in Stability - for example, when you decide to go on an EQ building spree - but if you’re not planning on going all-in with this ability, you still want to be building Garrisons eventually. However, being able to even delay building Garrisons can be rather useful, since you can use that Industry to build something that can give you more immediate gains. 

It should be noted that between Microbiology’s Mass Vaccination and Hospital, as well as Urban Planning’s Police Force, the Industrial Era can effectively solve your Stability problems, even if you’re in the negative. This means that by using this strategy, you can simply delay your Stability problems until the Industrial Era (or the Early Modern if you take Joseon), where they can be swiftly solved via rushing those two technologies. This fact can reduce the drawback of this strategy, since you’ll be guaranteed to be able to get out of Agrarian or Builder Cultures by the time you reach the Industrial Era. 

Something that’s rather notable is that this strategy flips the relation of Tall and Wide with Stability. It’s far easier to get a single City with multiple Territories to grow a single Population per turn or build Districts every two turns, than it is to get multiple Cities with fewer Territories to all do the same thing. It is easier for a Tall player to use this strategy and get no Stability problems, than it is for a Wide player to use the strategy.

In addition, as several players have noted, Tall playstyles typically have larger Stability problems, meaning that Tall players will have more to gain from using this strategy. Indeed, by using this strategy, Stability problems are completely eliminated, which removes one of the major drawbacks to a Tall playstyle. The existence of this strategy alone can make Tall playstyles more viable. 

So, in conclusion, usage of this strategy can arguably be a game-changer for Tall playstyles, making them, as well as Agrarian and Builder Cultures, much more viable. Whether used in moderation to delay your Stability problems, or going all-in and spending the entire game at negative Stability, this strategy can vastly increase the amount of Industry at your disposal by eliminating the need for Garrisons and Commons Quarters. 

Yes it is how you really get good value out of builders and agarian affinity, the passive stability bonus can be very powerful if you can make good use of it, but as you point out it do have a major risk in that you become dependent on keeping those affinities from era to era.