That’s not what they are doing right now
I’m also going be real that this is also the least of my concerns for a platform. If they make some people change their handle that don’t need to, it really isn’t a massive deal in the grand scheme of things. Especially since when handles are changed on Bluesky, all the references to that handle also change because they have a constant ID for all accounts. Impersonations leading people to scams is a much larger issue
Helpful links on how to delete stuff that’s meta owned
Permanently Delete Your Facebook Account
Permanently delete or deactivate your Instagram account
Deleting your WhatsApp account