Knew that Spielberg and Scorsese would come up and I was dreading reading the names lol. C'mon. If they're overrated, then everybody who is given any positive regard must be because they are, in my opinion, deserving of every accolade and positive comment they get.
If your system for gauging the quality of the director is that every single movie is stellar than you have an argument. Both guys have had their missteps. But that is not the basis for gauging a body of work. Spielberg and Scorsese should have cachet for life for films like Jaws, Raiders of the Lost Ark, ET, Schindler's List, Jurassic Park/Goodfellas, Casino, Taxi Driver, Raging Bull, Wolf of Wall Street, etc.