I'm a bit curious about this point here, but I might as well give my reasons while I wait for an answer.
Reasons: I tend to know my stuff when it comes to fighting games and just overall balance. I also sometimes have a knack for finding some rather odd bugs and infinites in characters. I've also been trusted with private betas before and haven't leaked them. I've even kept them entirely under wraps unless the author specifically said it was okay to talk about them/show footage/screenshots/whatever. I imagine you've seen my feedback before, so yeah. :V