Whether a person is a fan of MCU or not the thing is -everybody knows what a good show is these days. That casual or non Marvel fan has still watched GOT, Breaking Bad, Ozark, Lost, Mad Men, The Sopranos, The Walking Dead, etc. People are now knowledgeable about plot, character, pace, story, good acting to reel them in and wanting to watch the next episode to see what happens next. No matter if its a MCU show/movie or not, MCU still falls under these same guidelines when it comes to tv and movie making. Some people want to skip that fact all the time when it comes to MCU and comic book films in general.O i agree there is still a narrative being told. I also understand we are going from 3 movies a year to 4 movies a year/4-6 tv shows a year as well so there's multiple plotlines all moving(Multiverse/Thunderbolts/Young Avengers etc). I'm also a mcu nerd though and that's asking alot from just a casual viewer. There's no big overarching threat for the casual fans to be aware of right now and without that connectivity people are saying it's "boring"
At the end of the day these movies are still doing ridiculous numbers so it's all just chatter amongst the fanbase. As someone else said on here Marvel has no competition so people are just comparing it to themselves at this point.