BG3 is a sequel to a classic game by a successful RPG developer that was making good games in the same basic vein prior.
Name recognition, nostalgia, good reputation, no BS monetization, and not trying to copy and shoehorn every new fangled AAA feature into the game to keep up with the Joneses but focusing on what this kind of game should do best all went into BG3.
Bannerlord actually has a lot in common with it, the big differences being TW is like 1/4th the size of Larian's BG3 team, probably had less money thrown at them to make Bannerlord, and they were more indecisive about the direction of the game during development - which is also a more complicated game in some ways I would think - the turn based with pause formula is not very demanding compared to the kind of crazy stuff Bannerlord's mass real time combat involves.
So I don't really think there's that much for them to learn or that they deserve flak for not being Larian, which had the fortune of a variety of things converging in their favor when they were given a major IP to work on. Credit is certainly due to them for handling that opportunity better than most would, however.