It looks like @glenalbrethsen already got a great response to you, but as a decentralized platform, it's hard to remove people from Steemit. A while ago, I saw a screenshot of an account that was purported to be deleted, but I don't know if it was legitimate. As far as I know, accounts can't be deleted.
Still, there's got to be something that can be done to cut down on wallet spam. The wallet should be one of the safest tabs. You have some good thoughts and I really appreciate you commenting. :)