People might fight a lot of enemies in their MMOs, but a number of players will agree that there's one enemy that is bigger than anything else: the company that makes the game. Blizzard, Square-Enix, Funcom, Bioware -- according to this branch of the playerbase, they don't care at all about the people playing their game. All they're concerned about is making money. They just want to get your money by any means necessary.
However, the people who claim that say that like it's a bad thing.