So I have a slightly different take on this, and why the green and red balls are important, and they have to do with credibility.
Back in the good old days, underneath your avatar and handle, you'd have a post count. This post count would give someone, not intimate with the forum, a very rough idea of who knew what they were talking about and who didn't. It was FAR from perfect, as there was always "that guy" who was obnoxious and confidently wrong and had a MASSIVE post count, but it was something.
Then the world of social media popped up. Suddenly a bunch of the old forums died off, as traffic and new blood were diverted to things like facebook groups. There you haven't a clue who is trustworthy and who is trolling, it is just a seething mass of human. This lack of incentivization for quality content ultimately is leading to facebook's doom, as most groups seem to have trolls and contributors in equal measure.
Moving back to the forums, as hosting became cheaper and software features more plentiful, someone introduced the idea of a "karma" feature. I've seen it executed on forums in varying flavors, but this red-green ball system labeled "accuracy" I think is my favorite I've yet seen. It too is imperfect, like all human systems, but it gives users at least some reasonable idea of who is a newcomer and who is a greybeard, and also the quality of their contributions. It also, without the interference of the admins/moderators, encourages people to be polite. I genuinely believe this is part of why this is the most polite and trusting forum I have EVER seen. The anonymity of it helps keep things fair too, so that people don't spiral in positive or negative ways.
I also feel that, imperfect as it is, the system does significantly help with transactions. Users who contribute good content and have been around the forum are more trustworthy, and maybe you decide to use paypal F&F to send money to them. Maybe another user is rude, and if you're rude to a stranger for no reason, what will you be like as a seller/buyer when you now have money on the line? It gives you an idea about the character of the person you're dealing with, without being obtrusive.
And finally, on a personal note, I'll say that I like the ball system and feel like it encourages me to be my best self. I don't ever solicit green balls because I don't feel it is appropriate, but I get a little swell of pride and satisfaction when I make a post and someone appreciates it. This is especially the case if they sign their name to it. As any economist will tell you, incentives matter, and as silly and arbitrary as it is the system makes me want to be polite and write thorough and thoughtful and hopefully helpful posts.
So yeah, in summary, I am in support of the feedback system. I think it is relatively unobtrusive and has overwhelmingly positive effects on the forum, whether you like it or not.
My 2c.
