I have met people that make themselves feel better by belittling others. Perhaps that is one reason. I think that's a valid reason to have a nasty comment removed. I also can understand why many would feel that it's a troll. Most trolls like to sweep in, drop a bomb and as they're leaving look back to see what havoc they've wrought. For the most part there's nothing useful or constructive in their comments. I can see having comments like that removed.