As long as there are areas in the game where massive amounts of players can gather, that is a part of an MMO. The size of a group does not determine if it is an MMO or not. Are you going to claim that games like Neverwinter or Star Trek Online are not MMOs, because their group sizing is limited to 5 people? Same with ESO, most content only allows grouping of up to 5 players. If Counter-Strike doesn't have hub areas where large groups of people can be seen at once, probably not an MMO. Same with Starcraft. The only game where I've ever seen that actually had massive amounts of players in areas at one time was Defiance, though its group sizing was around either 4 or 5 people. No idea why you tried to be sarcastic with Dark Souls, as far as I'm aware, it doesn't have hub areas where you can see large groups of players at one time.