If we're talking about the vague cliche threads that spout off some old proverb as though it has any worthwhile meaning, I always attributed it to a desperate attempt to appear interesting or thoughtful while (unfortunately) the person had nothing worthwhile to say (prolly' due to a general lack of brain activity)
:-D
It's the cynic in me, when someone says something vague and basically meaningless or pointless conversationally, I tend to assume that it really was meaningless and pointless, and the person was just trying to sound interesting.
I attribute the rest of those posts to a LOT of boredom.