People might use this instead of banning (to free up resources or whatever), which won't be effective. We don't have to care, but we should at least consider it as a possibility.
Needs special-casing for the server owner so they can't delete their own account.
Messages would need to be deleted as well, or clients would just have to assume not having a user means it's deleted (even though it could just mean one didn't send for whatever reason)
Idea: Delete users
Why?
Problems: