Maybe they thinked about xmpp open to registration like standalone. Like the scribe that everyone can sign-up and "take" the username from people at disroot.

The xmpp addresses will be for your account @disroot only so noone can register your username at getgoogleoff.me or disr.it to take it for xmpp like people can "take" your user at git scribe and nexcloud i guess on disroot

I even registred at scribe some hours ago so no one takes hate from me lol

People are saying aliasses because they will not be logged on each account so they will not see the mess like three chats for the same conversation.

Make it separated hosts so will use it who wants to. Not a big deal for people that will just use disroot.org but a life changer if someone wants to use getgoogleoff.me or disr.it for another purpose and keep chats separated.