The way it works is communities are hosted on the instances and when moderators do things in communities that makes people mad those people can only go to that community’s instance administrators.

And then people get really angry at instance operators and admins with differing policies and rules about content and moderation.

So those conflicts can and do drive some culture wars. (Ex: Blahaj has little tolerance for gatekeepers, .ml has no patience for american liberal politics, .world is particular about zionism, and so on.)

But otherwise except for instances that defederate from each other the perk is absolutely that instances don’t really matter for registering and posting as a user.

At most just check the instance rules before posting and you’ll probably be just fine on Lemmy.