People will leap at any opportunity to give advice, because giving advice a) is extraordinarily cheap b) feels like charity and most importantly c) places the adviser above the advised. It's the same impulse which drives us to pity; we can feel superior in both moral and absolute terms by patronizing others, and unlike charity there is only a negligible cost involved.

I, for example, have just erased a sentence giving you useless advice on how not to get useless advice in a comment to a post talking about how annoying unsolicited useless advice is. That is the level of mind-bending stupidity we're dealing with here.