I've noticed that plenty of really old questions get bumped to the top of the page by answers of "I have this problem too. Please help!" or "That answer worked. Thanks!", and even when the mods delete those answers, the questions stay bumped. We tell people that such remarks should be reserved for the comments, but the people writing the answers are new users with only 1 reputation.
Wouldn't letting anyone comment anywhere give new users a non-answer way to give input on posts? Granted, we'd have to seriously monitor flagged comments, but I think it'd still be better than filling up the homepage with resurrected old questions.