We've seen people use systems like the one desired above on other sites. It led to an over-bureaucratization of the forum in question. It wasn't worth the effort, and (other than for spambots) that forum had a far more lenient system for dealing with rule-violators. Numerous warnings before each temporary ban, then several such bans before a permanent one. Still people ended up banned. Many more than get banned here, and still they demanded more "for justice's sake".

The fact is, the only ones who tend to care about bans is the close friends of those banned and/or those who simply don't like any sorts of authorities.

The cost-benefit ratio is decidedly negative for this sort of concept. At least that is our opinion.