That's because just about *anyone* can play the "suit" in a superhero movie as long as they act mostly like the audience is expecting. Basically - a script that's "true to form" for the guy in the suit. Most of those movies require very little in the form of "acting." As long as you can say your lines and don't sound like you're reading them you should be OK.When it comes to stage (or screen) actors, the younger relatives think actors/actresses are the ultimate "theater nerds". They don't have any notion of a "movie star".
This is all in spite of being raised watching a lot of superhero movies. It is as if the "character" is everything, while the underlying actor/actress is mostly inconsequential.
There have not been true "actors" in movies for several decades...