While I respect how you want to manage your game experience, game developers do not.
Not just Small Giant/Zynga. All game developers.
It’s a well-established rule for milking the most money possible out of massive multiplayer online games using micro-transactions.
What you do is this: you create a aspect of your game that uses clans/alliances whatever you want to call them. Groups of people. By doing so, you create an environment where humans bond with each other. Then, you rely on the social strength of these bonds to keep any particular individual human invested in playing your game longer than he/she would likely do if they were playing it all by themselves. Friendships develop. Gaming support networks develop. Game experiences are shared (good or bad). Game frustrations are shared. When an individual is thinking of quitting, they hesitate, because they enjoy the social structure of their clan/alliance.
So if your alliance is only two, and you only wish to limit it to approximately four, that’s all good for you.
But it’s not what the developers want you to do. Because it’s easy for a small number of 2 or 3 or 4 people to all be frustrated at the same time and to all quit at the same time. But if it’s 2 or 3 or 4 out of a group of 30 players, you have many other voices offering calm support, or soothing understanding, or shared venting, and you tend to stick around because of the bond of the others.
Small giant understands this well. So they have crafted a game element that rewards clans/alliances that are full (or at least “fuller”) and denies those rewards to small alliances or individuals who refuse to partake in an alliance.
It’s all about forcing you into a setting where the setting itself becomes a force to keep you playing.
So it will never change.
It’s a tried and tested game design. If anything, all game developers worldwide are only seeking ways to exploit its nature even more efficiently and effectively.