ultimately the discord thing isnt going to mater much because it's going to just have people doing "bob" and "Bob1" "Bobfour" "Bob1234" as opposed to "Bob#0001" "Bob#0002" or whatever so yeah there will only be ONE bob but there will be 99 million variations of bob because it was taken already as your primary username.
But that really doesn't fucking matter since it's like your account login in and your display name can be Bob. So you can have a server with 1000 people and everyone can set their display name to bob it will not break the server or anything
Sooo yeah it's overall... more of a infrastructure move or backend move for them and then everyone (or seemingly) freaking out that can't all be bob anymore