I completely disagree with the conclusion. "Playing through a story will always be LESS believable in a single-player RPG, EXACTLY BECAUSE the player really *can* change the world."
Do you find it believable that you save the world?
I find it much more believable that I'm one of the countless grunts fighting in the battlefield. I see other players and NPCs doing their part.
Yes, apparently it is not believable that in a fantasy game, people do fantastical things. One of the foundations of fantasy in general is how a person does extraordinary things, far beyond what would be expected of anyone. It's not supposed to represent the majority of the population who till fields and get shot in a trench. It's supposed to represent the few who did something bigger than normal. The spy who uncovered the plot, the assassin who killed the general, the lone survivor of the attack which sunk the ship which saved the battle which conquered the seas which won the war.
We're the .00001% of Azeroth. We're not believable and we're not supposed to be. We're different people in a different universe.
But is this any surprise from the person who does not wish to be a hero in a game about heroes, but merely a cog in a machine? It makes me wonder, if he wasn't so full of hate, would people then notice that he is a remarkably boring person?