I recently had a few people flame me in another thread because I corrected someone's grammar in - what I thought was - a fairly polite and decent manner.
I don't see why people care if grammar is corrected on a message board. In fact, I think people should take it as a blessing when someone points out an obvious grammatical mistake.
I understand the ridiculousness of pointing out various spelling mistakes and typos, but grammar is another story.
People judge you based on your diction whether you like it or not. Correcting a statement like "less and less running shoes get stolen every year" actually helps those reading who might not otherwise know that it should be "fewer and fewer running shoes get stolen every year."
I am not saying that making such a grammatical error automatically means you are stupid or uneducated, I think we all make grammatical errors every day. I am just saying that others will judge you that way.
Therefore, pointing out such errors on a message board enables everyone to learn the correct way of saying/writing something, without anyone actually getting embarrassed.
The next time you are giving a presentation, teaching class, speaking with parents or even just chatting at the pub, you might remember the correct usage and everyone wins.
I am not sure how an anonymous correction hurts anyone's feelings. I have been corrected on this board and learned from it. It did not anger me, in fact it relieved me. I wuld much rather be corrected here than in the board room.