Me, I'd rather participate on a site where I know the guy running the place has a clue about the stock market in the first place.
It's really a kind of paradox. Jeff and Brad started SI because they were also into the stock market. Once they started it, though, they backed off the public posting about it or particular stocks, until Jill then I took on the admin role, somewhat freeing them up to opine about the market.
Of course, it's expected that someone who runs a site where people talk about a particular thing should have an interest in that particular thing. But in the big leagues, that has to be put aside (IMO) and replaced with just being into message boards.