Which is true -- if you're actually the one in charge of groups. I'm of the opinion that it's very possible to play a game like WoW and get a nice boost to your leadership skills (leading a guild is often a job in itself), but I think it's also very possible that you could play WoW and not get a thing out of it -- I know quite a few people I've grouped with that I'd never want to have sitting next to me in a real office.
The bottom line, as always, is somewhere inbetween the two opinions. If you're already interested in taking charge and being a leader, WoW is a great simlulation to let you do those things. And if you're already a lazy worker and interested in helping yourself more than whatever team you're on, WoW probably won't cure you of that (there are certainly plenty of selfish people running around the game every day). In short, if your hiring policies are based on whether or not someone plays videogames, you might want to reconsider them completely.