If we set a cookie in the browsers of all Wikipedia visitors, anonymous or not, we could the assign them random global user IDs. Instead of banning users by IP, we could ban them by GUID, which would eliminate the risk of accidentally banning legitimate contributors.
While the majority of users have cookies enabled, a minority does not, so "soft bans" as I like to call them would not work for them. Other users might be smart enough to turn cookies off to avoid the ban. But I consider both beyond the technical understanding of most vandals, so I think soft bans might be quite efficient.
What do you think?
Regards,
Erik