"True, but they usually put you on ignore as soon as they sent it so you can't get even!"
Perhaps instead of the mutual masturbation that is "member mark exchange" a system where we agree to send PMs on behalf of those who have been sent an abusive PM then been immediately blocked would be beneficial.
For instance if somebody sends Churak a rude PM and then blocks him before he can send a reasoned and cogent reply (I know, I know, but bear with me here, it's just a hypothetical example), he PMs me with the text he would like the offender to receive and I forward it to that poster on Churak's behalf.