I think the Ban Request section is  certainly useful HOWEVER I do think a lot of the people in the community use it to lash out at one another.
That's just a result of people taking this way too seriously.  I find it to be humorous.
I have only ever posted one ban request, and it was for a guy who over the span of several maps was opening the gate (as defenders) and TKing people.  He was treating the 5 warnings as his allowance, and TK'd his friends who did not [M] him.  That pretty much ruined everyone's game.  Defenders loved  the free multi until they got autobalanced onto the losing team cause of GTXters.  

For the most part I think it's all pretty harmless.  Accidents happen, no reason to hold a grudge or OMG THIS GUY IN CHAOS IS PURPOSEFULL TW'ING ME!  It's purposeful  BECAUSE HE'S IN CHAOS and friends with all the admins!!  Yeah great logic.
TL;DR Ban section has a use, but I agree that people often use it as a tool to get "revenge" on somebody they dislike and that's just a bit sad.  Fortunately, we do have smart admins who review the cases, and sometimes even ban the OPs for instigating the response from people.