Did Roger Staubach make Landry look great? Landry won a lot of games before and after Roger, but only with Roger did he win championships. Did Walsh win anything without Montana? Would Jimmy Johnson have won anything without Aikman? Lombardi without Starr? Noll without Bradshaw?
You could put this qualifier on almost any coach. Siefert won with 2 different QBs, yet he wasn't worthy of carrying Walsh's clipboard.
Don Shula is unquestionably one of the greatest ever, but he won SBs with Griese, then couldn't win with Marino, easily the greatest QB he would ever have.
Colin Cowherd said that of all the players, ex-coaches, etc that come on his show, there's almost uniform agreement that Belichick is the best coach in the NFL and no one is a close second.
It would be hard for me to make a list of the 5 greatest coaches of the SB era without including Belichick. Yeah, he had Brady, but he also often had teams that didn't have a dominant player apart from Brady. Yet he's won 3 SBs, and won more games over the last decade than anyone every has over a similar timeframe. And unlike most of the other guys, Belichick did all this in a league more set up for parity and in the era of free agency and the salary cap.