Rings come into the argument, but the people who think it's a requirement to be an all-time great are completely mistaken. There is way too much going on in a football game to have the expectation that every great QB will win a title, or that you can't be the greatest without multiple titles.
Look at all the guys with 3+ titles:
Brady - all 5 SB appearances with Belichek, only one SB appearance with less-than-great D
Montana - Beneficiary of Walsh's west coast offense, and the greatest WR of all time
Terry Bradshaw - No need to say anything
Troy Aikman - everyone knows it was about the D and the run game
It's an exclusive group, but by no means is it an elite group. I don't think Bradshaw and Aikman are even HOF-worthy. If you can be as mundane as Bradshaw and win 4 super Bowls, what does that say about the accomplishment, and what is required to achieve it? To me it means that a good deal of it is out of the QB's hands.