You listed two backups who played a handful of games combines and a few guys carried by all time defenses. The other QB's weren't elite but were good enough to get their teams to the playoffs and got hot at the right time. A few QB's out of 50 some odd Super Bowls doesn't prove anything.
Why would what they defense is matter if it’s all about the QB? QBs being carried by their defenses is contrary to your argument and ultimately almost every QB you would consider THE reason his team wins, won 1 or maybe 2, and only did so when their defense was strong
How does “not elite” but good enough to get their team to the playoffs and get hot support it’s all about the qb?
Hoe many QBs that won SBs were the best qb in the league at the time?
Not many. If it’s all about the qb why does Eli Manning have more rings than Dan Marino?
Why did Peyton Manning stumble into one his entire career besides the one he got that he had nothing to do with?
Counter my list (off the top of my head, there are surely more) with seasons where the best win in the league won the Sb?
It won’t come close.
The bottom line is there is correlation between good when play and winning, just as there is to good enough play, good defense, special teams and right guard play. It’s a team.
Of course good QB improves your chances, but that’s true of any position. The game has evolved to a point where the QB is the most visible, popular, and enamored player, and while he is also the most important player, the popularity and misconception that football is qb vs qb is blown multitudes out of proportion.
People focus on the name players, but those name players only win when the entire team is good and everyone does their job.
Again if it were all about the qb the best QBs team would win every year.