it won’t take long before the community is split on one.

People are always "split" on all kinds of topics.. Conflicts and disagreements are part of the human experience and impossible to avoid.. The question is how you deal with conflicts.. Trying to avoid or suppress them doesn't work..

Who calls the shots when everyone has equal say?

Nobody calls the shots, that's the entire point.. People are free to form communities and run their communities however they see fit.. If a community has an issue with another community in significant enough ways, they will block each other and that's it..

And it's not like this is anything knew.. The internet is inherently diverse when it comes to different opinions, and that's ok..