"How dreadful!" cried Lord Henry. "I can stand brute force, but brute reason is quite unbearable. There is something unfair about its use. It is hitting below the intellect." ~ Oscar Wilde - The picture of Dorian Gray
Truth is, only a select few boneheads actually earn banning - even then only as a final solution after vast opportunity to reform/mediate their particular pattern of hostility. We're pretty easy-going.
We have detected a bone head! We will now persistently warn them to shape up, and after giving them various chances and warnings in an attempt to make them repent their evil ways, we are going to stick them on the radar, and if they refuse to shape up, they will forever be sent to the lacking-of-fluffy-bunnies world of the banned!