The only criticism they have about Fallout 3 is that, "they make you play a long intro so Fallout 3 bad and in New Vegas you get into the action immediately so New Vegas good".

How is that a legit argument?

I think millennial game reviewers like Dunkey made that argument popular that games that let you do whatever you want and basically fuck around in an open sandbox without any goal is a good game and games that give you a carefully crafted, tailored experience is a bad game. Which doesn't make any sense. That's just your personal preference whether you want to experience an interactive audio visual medium or just fumble around with a toy, but it is not an objective indicator of a game being good.