If the account has posted or has sent/received a PM then it absolutely should not be deleted.
I think even in the 'perma banned' scenario you want to leave that name banned. Otherwise how do you prevent either (1) the perma-banned user simply resigns up under the same name or (2) some other user signs up under the banned name? In (1) the perma ban has failed. In (2) an unwitting user just inherited a terrible reputation.
Solution - the name remains "taken"
Yes. As far as I can tell, you completely agree with me. The name remains "taken" which is equivalent to not deleting it which is what I'm arguing for.
Remaining taken is different from not being deleted. With many websites, even after deleting an account, the account name remains taken.
What's the point of the deletion then? I thought the OP was suggesting to delete old accounts so that the usernames could be freed up for new users. If that's not what this discussion is about, then I've missed something important.
There is no point. It's a not a good idea and will never, ever be implemented on a forum like this. Recycling usernames doesn't work in a community where financial transactions are taking place.
Sounds like we agree with each other. This is just semantics.