Because let’s say you’re Tom Hanks. And you get TomHanks@Lemmy.World
Well, what’s stopping someone else from adopting TomHanks@Lemm.ee?
And some platforms minimize the text size of platform, or hide it entirely. So you just might see TomHanks, and think it’s him. But it’s actually a 7 year old Chinese boy with a broken leg in Arizona.
Because anyone can grab the same name, on a different platform.
Because it’s not centralized. Every platform/instance just uses the same protocols. Any that try to go against that get defederated by all instances.
How do you identify them? Lemm.ee registers Tom Hanks, does every other instance have to check what information they provided to trust them?
What prevents someone to bribe a small instance to register a celebrity username on their instance?