The one bummer I have about Mastodon is that it takes what used to be a kind of sort of meaningfully understood usage of @ and turns it into scrambled eggs with @user@instance.social for it's usage in use names. It's the one place where I would begrudgingly acknowledge that blue sky has a compelling rationale.

And yes I'm aware that Mastodon omits the second @ for users on the same server, it's a imperfect compromise that sometimes helps but largely leaves the problem unresolved.

Arguably, the fediverse got it from Twitter, and Twitter got it from the syntax of email addresses, which came from Unix user@domain account signifiers