Idk about this stuff because I'm a functioning adult, so maybe out of the loop or something, but didn't the MCU make a ton of money and then pretty much sink without leaving a cultural trace? Extremely online blue checkmarks consooming random spin offs on boutique streaming channels doesn't count.
Apart from a few memes, and some increasingly hazy memories of seeing THOR VIII: IT'S HAMMER TIME (or was it DR STRANGE VERSUS THE CHIROPRACTIC WEIRDO?) what's the real world legacy of the MCU to normal people with lives? It was a popular theme at kids parties for a while, but that's died off. Compare to the impact the original and good versions of Star Wars and Star Track left on popular culture: everybody knows "use the force", the Imperial March, "I am your father", "Dammit Jim, I'm a doctor, not a X", etc. Luke, Han, Leia, Chewie, Kirk and Spock are still famous and beloved characters. Politicians would quote them, commercials would parody them, NASA named a shuttle after the Enterprise. It was part of mainstream vocabulary long after those properties left the movie theater/original TV run.
Do you see any of that happening with Ant Man or Iron Man? I don't. Even THE MATRIX (1999) still has more cultural cachet than Endgame (2019). See also: ALIENS (1986), TERMINATOR 2 (1991), and plenty of other crowdpleasers that left an impression on the audience longer than it takes to find your car after the credits roll.
Not the first time that's happened either. AVATAR grossed a billion dollars 10 years ago and nobody remembers it now. Something about blue furries? Couldn't name any of the characters or tell you a single line of dialog from that movie even though it was spunking 16.7 million color CGI into everyone's eyeballs in full 3D and broke all box office records in history. (TITANIC, Cameron's previous and less dumb blockbuster, is still something people recognize)
But why? I'm not a film snob and it's silly to pretend ROTJ was a cinematic masterpiece (people were already getting tired of Star Wars in 83) or that the one where Spock saves the whales is Citizen Kane. But the older movies tend to have more going for them than 45 minutes of computer generated punching and every solemn character moment immediately being undercut by a snarky quip.
So Bob, being Bob, got this completely wrong again and Martin Scorsese was right. Capeshit isn't a religion, or modern mythology, and they're barely even movies. They're theme park rides, people enjoy them briefly and then never give them a second thought.
Unless they're horrifically obese 40 year old manchildren who are too fat to fit on theme park rides, and need to use some kind of homemade periscope to see their own penis.