These films are technically competent to a fault. That fault of being uninteresting and unmotivated. And the only thing they have going for them; is the speculation and hype that fans and media generate surrounding them.
So all of this is to prevent spoilers
Which to quote a very famous film analyst, “if your film would be completely ruined by a spoiler your film is actually bad.”
It’s also a way to control the actors. With more conventional ways to communicate and manage films, actors have recourse if they think they’re treated like shit, and ways to influence the end result of the film.
But the MCU way they can shut that down. It cut all recourses, so the exec and prod have full control of the actors. Can’t protest and suggest things about the scripts if you only get it from an unknown man behind the local supermarket. Can’t show support with your colleagues when you don’t even know who’s in this movie.