That's a list designed to make people mad IMO. Or was just written by a dope. I'm not sure there is any underlying logic to it since it's a mish-mash of genuine greats, people who just threw a high volume of passes, and guys with rings who were otherwise pedestrian for most of their careers.
Staubach is probably underrated even by Cowboys fans, never mind everybody else. Accounting for the era Staubach was basically Aaron Rodgers, only with more comebacks/game winning drives in fewer games played and more titles. He was that kind of HOLY CRAP player in his era that combined mobility with very high passing efficiency compared to his peers and big play ability.
Roethlisberger was the ultimate "just along for the ride" QB in 2005 who tried to choke away that Super Bowl but failed because of the defense and run game (and refs screwing over the Seahawks super hard). He has a long career of being nicely above average but not much else. Also he's a multiple "alleged" sex offender who deserves the respect of nobody.