Domains was invite and hasn't died. I don't think this is necessarily arbitrary. It's quite possible they estimated "Our servers can take N users right now and

Domains was invite and hasn't died. I don't think this is necessarily arbitrary. It's quite possible they estimated "Our servers can take N users right now and we'd rather do features than scaling while in a 'beta'". They might just need to scale-test before opening it up, and invites allow them to get user feedback without risking ungated floods which crash it all