Actually, that could be the reason why sometimes the user finds things unacceptable, because some instance owners treat their instance like their "own little walled garden." It's a real pain to shop for an instance when you don't want a walled garden but rather an open medium through which to access content you wish to see. I see some instance owner decisions as reasonable (like staying away from misinformation and fake news) and I see others as a little bit unreasonable. I try to stay out of walled gardens. I like to roam free and make decisions for myself because I'm a smart boy, I know what I want and how I want it.

Not sure I understand your point - yes the runner of the instance has the ability to do whatever they want, but that doesn't mean whatever they want to do is a good idea. If the decision is implemented my response would indeed be to move to a different less problematic instance, after complaining a bit to see if I could get the decision reversed rather than having to flee.