Fediverse

Think of an instance like a vehicle (bicycle, train, car, airplane, etc.) while the content (posts) is the destination, which I guess makes the communities the city streets that arrange the content for easily going from one to the next. Anyway, the instance takes you “there” (wherever you want to go), but you can get there from most instances, or you can even make your own instance, so deciding your ultimate destination is not a great feature of choosing an instance (it's actually much more complicated than that, but to a first degree of approximation that much is true - you can pretty much access meme communities from any instance, or block those communities regardless of which instance you are on, as you choose).

At first there seems to be some exceptions, like startrek.website, but there too it's just a convenience factor - you can subscribe to those communities from anywhere (that federates with it, e.g.lemmy.world) - or you can be on the startrek.website instance but block every one of those local communities (if you wanted) and instead post and comment all across the Fediverse in other communities.

So it's not proper to look at the instance level for a solution to this issue. And as for the community level, setting aside the communities dedicated to memes on purpose, the prime issue of memes appearing everywhere seems to be moderation or more apropos lack of it. If you wanted to start a serious community, about e.g. philosophical discussions (which already exists btw - press the community button and search to find several), then you could put in the actual effort to keep out such lower-effort content that you do not like to see. And if you do not like it, surely there are others who think the same. But somebody, somewhere is going to have to expend the effort to make it happen, or else it simply won't.

Also here's a fascinating essay on the subject: https://medium.com/@max.p.schlienger/the-cargo-cult-of-the-ennui-engine-890c541cebcb. Reading that is a large part of what made me leave Reddit, and almost Lemmy as well, but being forewarned is forearmed so now that I know, I can limit myself and be alright with how I use social media. It's a really good read!