In the world of “stack overflow is unfriendly to new users”, banning a person providing an answer that other people have found helpful seems to be a suggestion that would take SO in the direction of yahoo answers.
Stack Overflow’s approach appears to be all answers are acceptable. This isn’t just for the person who asked the question but everyone else too.
If a person is not providing good answers and people are down voting those poor answers, there is an automatic answer ban in place... but that requires people to down vote poor answers.
