Even thinking of it in terms of non-fediverse platforms. reddit often had multiple subreddits about the same exact topic. But the communities were different, often even splinters from each other because of disagreements on content and moderation. You end up with the original sub, Foo, followed by FooMemes, and TrueFoo, TrollFoo, FooJerk, etc.

If communities start getting merged together automatically, it’s going to end up causing problems. Most likely the culture of someplace like lemmy.ml will end up being marketedly different than some other instances (and already is). I would not want posts from a memes group there mixed with a memes group from elsewhere. Grouping the same post client side, sure. But there’s a reason for separate groups about the same topic.

ehhhh, don’t throw the baby out with the bathwater! personally i think it makes vastly more sense to federate on a per community basis rather than a per instance basis. an instance is most likely going to hold a vast array of users and topics in an ideal world, in which case the general consensus on what is and what is not considered to be relevant or desirable content for the given group is likely quite difficult-- there’s nothing to go on, as everyone’s talking about different things and holds markedly different values because of it. But communities? Perfect sense! Every community is about a very specific subject/topic, and comes with a set of rules/values for everyone who wishes to post/interact with it. Once you get to the granularity of federated communities, it no longer feels quite so high handed to federate or de-federate with something, because the general consensus of the community is assumedly much more clear.

Sure, leaving automatic federating up to the client makes sense, but the meat of it sounds like a much better level of granularity for decision-making for something that impacting than it being server-wide…

But perhaps I am simply way off mark. my experience is small, in comparison to my conviction lol.