He was never a really great writer overall (he’s always been better at some aspects) nor a great director of actors. It really comes down to that he had a lot more critical voices at the time. He handed the original SW script around to his peers constantly and really honed it down to what it ended up being from the craziness that it started out as, which was far closer to the messiness of the prequel scripts (which likely didn’t have very many revisions at all). When it came to ESB and ROTJ, obviously he had others write those scripts entirely. Again for the actors, he was pretty lax about actors rewriting dialogue during the original film (whereas I doubt many of the actors felt comfortable trying to change things while shooting the PT), and then again on the other two he didn’t even direct them. Editing wise it’s the same idea. For the original film he screened it to all his peers and they trashed it and he took notes.

So I’d ultimately say that the idea that he was surrounded by too many yes men is true and that was the root source of the problems, though I wouldn’t necessarily say that he purposefully created that environment in which no one would say no, I think it just kind of happened because people just assumed he was a visionary that’d be able to make OT-level films on his own. And I do tend to think he’s a brilliant visionary but maybe not the greatest filmmaker. He’s talented in many ways as a filmmaker but not perfect and benefits a lot from skilled collaborators.