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.
We decided to not host any sort of Buy-Sell-Trade community on our hobby instance for this reason. It’s a small community so a lot of people know usernames of people they know and can trust. It’s very easy for a scammer to use someone’s username and say “I’ll sell you that thing! Send me $150!”.
I’m on MBin. Your username is displayed as: walden. I can mouse over that to learn that your full username is @walden@sub.wetshaving.social.
This is the same thing as email domain names and display names. Yes, scammers still exploit that, too, but for the most part, people have gotten used to also looking at the actual full email address, and not just the display name or mailbox name. The same can happen here.
Still, I would much prefer if the default view here showed the full username and not just the display name.
There is an issue on the Mbin repo asking for that as an option if you are or know a developer with free time