What Constitutes "Beating the Game"?

It's just personal viewpoint. Both sides have valid claims, but I think that a game is meant to be enjoyed however the user sees fit.

I don't think it's up to us to define what "is" or "isn't" really playing the game.

(But if you want my opinion, the experience of the game and all of it's quests and side stuff is the full picture, and sneaking through the game avoiding everything isn't realizing all the content).