I don't think it is that Belichick is against developing a QB. In fact, he has always been adept at that from Brady to Cassel to Garoppolo. I think Belichick played a big role in developing all of them.
I personally thinks he feels he can develop a lesser QB into a winner than he believes he has to draft a QB high because if you don't you cannot get a franchise QB. I genuinely think he believes he can develop someone like a Jimmy Garoppolo who was an unheralded second round pick into a winner and that is why he passed on Lamar Jackson.
This is why I think he might have traded with either the Giants or Vikings rather than draft Maye because he thought he could have made McCarthy or Nix or Penix a franchise QB.
He didn't select Lamar Jackson because he had an owner who gave him grief for having a plan to move on from a 40 year-old QB and he had a QB and owner clamoring for offensive weapons, so much so that they brough in the kitchen-cupboard and expended a ton of resources to get them (i.e. Demaryiuous Thomas, Killer Antonio Brown, Mohammed Sanu and of course, our favorite, N'Keal Harry). Given all the acrimony, I don't think taking a 1st round QB was in the cards.
And by the way, coming out of college many people would've thought that Lamar Jackson was a huge project in need of a lot of development, a project. I fail to see how people like Nix or Penix could be considered lesser while taking Lamar would've been something else.
It makes no sense to me anyway that someone would say, "I'll take Nix and prove I can win with him instead of the better QB Drake Maye." Especially given all the scouting beforehand about both QBs.
I've only ever heard Belichick speak about the importance of having a great QB and the need for one as it relates to winning.
Everything in his prior experience would've told him that a winning QB was necessary.
LOSING with Bernie Kosar, Drew Bledsoe and Mac Jones.
WINNING with Vinny Testaverde and Tom Brady.
How can we say he wanted to win with a mediocre QB when everything in his experience showed the wins come with superior QB-play, almost immediately when the team moved on from mediocre QBs?