Funny thing is, Steam can't be a monopoly, because there's Games for Windows and the same dumb people making those statements are also digital games distribution services. So it's a blind shot at some lawyer buffet who can milk money out of Steam and make them less profitable so THEY get more people. Cheap tactics are cheap alright.
Besides, like stated above, we can't actually tell if it is a monopoly, cause it doesn't look like one at first hand: lot's of offers, cheap/store priced games and friggin' sweet deals every F'ing week. If that's a monopoly, then they aren't so bad when in the right hands. Just like Monarchies and Dictatorships; sometimes, with the right people, they're actually good.
Funny to say the least, really.
Cheers!