IP blocking is an epic FAIL.
First, if you are connecting from your local Starbucks, public library, internet cafe or other public hotspot you have now caused all other potential users to be blocked.
If you connect from work, now all your co-workers will be blocked as well. This might be a good thing, but if you're working night shift and have nothing to do but pick your nose most of the shift it'd be cool to be able to play chess. Obviously businesses can't change their ip address easily especially if they are running a mail or other type of server.
If you connect from home, changing your ip address is about as quick and easy as a trip to the bathroom.
IP banning also punishes totally innocent people who "inherit" an IP address which has been previously been banned.
FAIL!
I agree with all that you say. I've also heard that changing an IP address is easy, but that was in C++ forum.
I've aborted several times because my opponent would not move. I've waited 3-5 minutes, and no response from them.