I'm pretty sure the users who get the abuse bring it on themselves. There are users who break this rule:
a dozen times a week yet go unpunished by the mod team, so it's no surprise that other users get frustrated by being fed horsecrap by certain posters, time and after time and end up telling these posters just what they think of them.
As it appears, you're willing to enforce this part of the rule:
Yet do no wish to take action against those infringing this rule
which is infringed on a higher basis than the " not being insulting and abusive" rule.