So are the number of problem users.
Really? The rate appears to have been pretty much constant for the length of time I have been around
Blocking open (not "open source") proxies is not going to get rid of CD or any other miscreant on dialup.
They are only one source of problems
How do filters help?
I can't cheack every edit on RC I have to use various methods to select the ones most likely to be a problem.