I’m seeing registrations for users whose “website” URL is very dubious (including adult stuff that would make most people blush). They’re obviously only registering for the link because they don’t leave any comments.
If the admin goes along with the recommended action of marking the user as blocked (rather than deleting), then their link is still visible in the profile page. i.e. They win.
So I’m imagining a core enhancement or a plugin that adds a filter so that any user who is marked as bozo/blocked has their details passed through a sanitizer which removes anything that looks like a URL before it’s passed to the UI.