Why ? Patreon exist since 2013, while I played my first adult game in the early 90's. Patreon or not, we will still have something to consume.
Asking for a change in Patreon policy is relatively stupid and useless. They will not listen, especially when the choice is either taking the risk to loose (now less than) 10% of their customers, or taking the risk to loose their whole business.
As for the creators, they are grown men and women. Patreon have their Terms of Services easily available and you're surely given a link to them when you create a page as creator. It's up to the creators to read them, then either agree or use another platform, period. And if they haven't read them or wanted to play with fire, it's their sole responsibility.
The only consequences they can't avoid are the legal ones. You think their ToS aren't clear enough ? You think they banned you despite their ToS ? Go in justice, period. Except this legal aspect, they are your host and have all the rights, while you are the guest and have nothing more than duties.
As for you, you just have the right to agree or not. But in no way you have the right to say that devs shouldn't use Patreon. It's their decision and, whatever if they have or not legit reason for this, you have absolutely no say on it.