I really respect Stan. After all, he (and Steve Ditko) created my favorite superhero of all time, The Amazing Spider-Man.
But here's the thing about the existence of “educational value” (and I hate having to say this): 1 is a value, but 10 is a greater value than 1. "It's impossible to write a story without a message," yes... but "family is important" is a message that's repeated all too often throughout cinema. You don't need nine Fast & Furious films to repeat the same message.
That's the thing Scorsese was pointing out. It wasn't that entertainment has no message; it's that they repeat the same message audiences are familiar with. There's comfort in familiarity. It doesn't challenge, it doesn't provoke. Unlike art. Scorsese seeks a value greater than “1.”