Out of the 150 games I've purchased through Steam, 150 of them work as intended. Clearly a scam, right?
Besides, Steam is just a redistribution platform with integrated DRM. It's almost never responsible for whether games work or not, it just sells them. It'd be like if you bought WoW at Wal-Mart, but then blamed Wal-Mart when you couldn't play it because you didn't have an internet connection.