This place is already moderated more than a prison yard at exercise time. About the only thing missing are the shotguns. The whole, "thumbs up / down" routine would elevate that to an even higher degree. Because it will only serve to intensify everything without adding benefit. Besides, everyone here comes for a different reason. And places whatever value they wish on these threads and posts. Advertising who votes for what isn't going to prove or improve anything.
As I said before, look at all of these, "Which Oil Should I Use?", threads. There is a new one every week or so. In 6 pages the guy will be told to use every viscosity, brand, and type known to man. The poor guy who started it leaves 5 times more confused than when he came. Now add a bunch of, "thumbs up / down" to the whole mix. You'll wind up confusing the poor guy even more.
People vote with their opinion, along with who and what they like. Just like they do politically. "Fact" rarely enters into it. And one man's "fact" is observed as another man's opinion. Because he believes something else to be "fact". And it matters little who is "right"... Assuming that it's anyone. Especially in a thread like I just mentioned.
Some people treat this forum like a form of entertainment. They stop by when they happen to have a few minutes, to check up on all the fresh B.S. Others like to share what they know..... Or think they know. It's up to the individual to weed through it all, and form an opinion based on what he values, likes, or sides with. And reject anything he doesn't. Not by trying to form some abstract opinion based on some thumb driven "rating system".
This all kind of reminds me of grammar school. When some kid would get up in front of the class and read his report. Then the teacher would start in with the whole, "Let's see a show of hands, class", routine. It didn't improve anything except frustration. By being graded by a bunch of fellow classmates who don't know any more than he does.... But think they do because they've all been asked to "vote".