On both admin and secure, users with a long profile blurb:
mysql> select * from user_profile where length(blurb) > 128 limit 100;
...are overwhelmingly spam accounts. These links are currently not nofollow, so there's some technical incentive for abusive users to continue doing this.
A secondary behavior of these accounts is to leave various comments.
Disabling users currently does not disable their profile blurb.
We should possibly introduce a new "Banished to the Shadow Realm" state which hides the profile blurb and all comments from a user. These users could also become invisible while not logged in (T12877) in all cases, regardless of other settings.