At one point Scorsese was sold that it was. You have a fake gangster with a book as the basis of a movie that the director bought/believed. The story is supposed to be an introspective look into this man's life. Over something that he didn't do. It is the most low stakes story.
Imagine a story about King87 as a lawyer where I convince five justices to change their judicial viewpoint in totality with my brilliant lawyering...except not only did I not do that, but I never passed the bar and died as a paralegal.
It kills the immersion. You can't walk it back. The immersion is killed with stupid CGI faces and stupid fight scenes that are part of the crux of a familial issue. "Wow, this is a great gangster movie," except it's not. It's a great movi about a guy who wrote a book about him cosplaying as a gangster. Most of the movie felt like it was about union politics and not a gangster flick.
We never saw the family be close with one another. So how is the cutting off between the daughter and father hard hitting, other than the assumption that it should be?
Fun fact, the old geezer who hated the Marvel Special Effects used those same ones, even some ones that marvel franchises created in his film...you know...to show us the 40/80 year old gangsters...
I have never seen a movie tell less story with so much time.