I think it could also be for the purpose of preventing imposters, as what Clyde says is what Discord says.
The discord username namespace is weird. You get to set a display name which doesn't have to be unique so you can have the name "Bob" and that's what shows up when you message people, but then you also have a unique version on your profile that looks something like "Bob#3922" I'm not sure what happens if 10,000 people pick the same name but as far as I know, there is no limitation to how many people can have the same username.
So it seems almost impossible that this is some technical limitation but rather Discord cracking down on a common deception tactic.
Re:“Username cannot contain 'clyde'”
by Eavolution on Monday November 21, 2022 @02:58AM
(#33690024)
It don't let you if there are no numbers left when I changed my discord name last
It's not always the wrong choice to mingle identifiers of different types, but I think often people err on the side of convenience (/ laziness) instead of thinking through all of the potential issues.