Since email is the common analogy, I would extend that to say that you could be John.Smith@gmail. You might also have John.Smith@outlook. Someone else has John.Smith@yahoo. If you wanted, you could setup a new account John.smith@protonmail, or start your own server and be me@JohnSmith.com
Communities are the same way.
Breitbart on the mainstream, centrist posts. Most of it's way further out there. I have no idea which ones are inauthentic shitposts and which ones are legit. They are way beyond Poe's Law.
But more important is when they show up on other instances. Everything becomes an argument, dragging down everyone and everything they encounter. This also can't be solved by just blocking the communities on EH, it must be blocked at the community's instance or our (the viewer's) home instance.