This is sounding suspiciously like those strange ideas that kids shouldn't be graded to protect their fragile little egos.
Feedback is essential to intellectual (and physical) growth. Incapable individuals don't know they're incapable. Telling them and demonstrating that they are incapable increases their capabilities, primarily by making them realise there is room for improvement.
I can understand rules enforcing civility. I can see a rule that states that any post which starts with "I couldn't be bothered to read the thread, but...", should be removed. Hell, I could even see rules banning non-constructive criticism.
I can't see the point of tiptoeing around other peoples sensibilities to such an extreme degree that you can't tell them that there is something wrong with their idea.