Because let’s say you’re Tom Hanks. And you get [email protected]
Well, what’s stopping someone else from adopting [email protected]?
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.
Except in this case, there can be no corporate green to destroy the fediverse. They can build and destroy their own instance, and their own communities…but the very nature of the fediverse is that it scales well, and it CAN’T be owned. So growth can only help. Temporarily it may crash the servers with more traffic than it can handle, but more instances and servers will be added, and the userbase will spread out.