Kinda, sorta, not really.

So on Reddit, the people who run the iPhone subs have iPhone 17, iPhone 18, iPhone 19, and so on registered and they're squatting on them until they become useful. Or Fallout 3, Fallout 4, Fallout 5, Fallout 6... Now what some people have done is add a word. Like you have the "Cyberpunk" sub and "Low Sodium Cyberpunk." That works. Or like you have Atheism, and you have RealAtheism. So you can put a word on it, or something like that. But you'll never be able to be the "original" because a small group of people control those.

Now with Lemmy, those same people will just make those communities on the biggest Lemmy instance, but they won't do it on all of them. I use Divisions by Zero, which leans a little further left than some of the others, it's more of a fringe instance I guess? They're probably not gonna target that. So if someone made a community and tried to divert views to their videos for profit like I said in my example, I could make a community with the exact same name on this instance. The other community probably wouldn't let me advertise it there. I could do it once and get banned and maybe get a couple people to join both, at least, but I could promote it on neutral ground, and people could decide who they want to support. Because of federation, even if you aren't on db0, you can still subscribe to a community hosted on it. Like this community is on lemmy.world and I'm subscribed to it and freely commenting on it (at least until/if lemmy.world decides to defederate the instance I'm on — they have that right and ability. But I could make an account on their instance or one that is federated with them. And that's kosher as far as I know, as long as I myself am following the rules of the instances I post on.