Oh yeah most of my favourite films would be films that I consider thoughtful, and Scorcese would consider "real cinema". But if you take something like La Passion de Jeanne D'arc, it had to rely on the intensity of the acting, the thoughtfulness of the cinematography and the strength of the script because the cameras were cumbersome and sound reproduction was impossible. The limitations of the technology required that kind of artistry and creativity just to make it worth seeing on the big screen. Godard, Truffaut, Fellini and co. grew up with films like that and as the technology improved, they carried a lot of that essence through to their films. And those are the kinds of films that Scorcese then grew up with.
These kinds of films didn't really come close to exploiting the power of an audiovisual medium just because the technology didn't allow for it. As the cameras have gotten lighter, sound and color reproduction have exploded onto the scene, etc. we are now much better at that. And you can see how that manifests itself in blockbuster films. So it's not that you can't make artistic films that appeal to a large group, but it isn't necessarily true that they are the pinnacle of that medium.
Something like a book has to work really hard to bring ideas to life, and it makes your brain work hard and slow. That's just one of the limitations of the medium and there are echoes of that in what defined cinema in the era Scorcese grew up in. But our eyes / brain process moving images exceptionally quickly, with sharply contrasting colours playing a big role in that, and loud noises play an important supporting role. Detecting lions in the grasslands and all that. If cinema's development wasn't artificially constrained by those technological limitations then it might be that these loud, colourful blockbuster films might have been defined as the pinnacle of the medium.
That's at the heart of the question Scorcese raised, and underpinned
@calodo2003's assessment of the decline of film. The idea that there is a "true" form of cinema, and that it was defined almost a century ago. At the end of the day cinema's just this thing we invented that has been defined and redefined over and over again. Experts like Scorcese should play a role in defining what that is but the default assumption that this recent progression is a decline should be challenged.