It's that John Romero, through the ad, was talking shit. Yes I know the ad wasn't his idea but he had the power to stop it and he didn't, so it speaks for him.
The reason he catches so much shit over the ad was because he couldn't deliver. The game did not make anyone its bitch.
So it's not that a bunch of gamers are getting their panties in a wad over this. It's that a bunch of gamers are having a good laugh at John Romero's expense because, like it or not, he went all in and lost.
In Romero's defense, the game was conceived, coded and delivered in less time than a single reboot of DNF.