I have a theory on Doc, based on my own experience in the corporate world.
Now he has certain qualities, I think he relates well to vets, gives his players a long enough leash, doesn't micromanage, etc. but his absolute best quality is that he is top-notch charmer/schmoozer. Dude can work a room, and this is why he has perpetually been employed.
And I don't say that in bad way, it's not a criticism, like he's two-faced, but it's definitely a skill that certain people have that allows them to constantly rise through the ranks or be heavily recruited elsewhere, a skill that helps them constantly out-achieve their own abilities.
Like he can meet with ownership, regale them with basketball stories and just enough high level strategy that everyone in the room will be convinced he's this great basketball mind/leader. He just charmed everybody.
Or he can meet with a GM (who actually knows the game), and quickly shift the blame for any shortcoming on to somebody else. Chris Paul struggles to get along with other players, Paul and/or Blake are injured, Ben Simmons can't shoot, Embiid was injured Giannis was injured. Dame was injured, etc. Charms his way out of it.
I think if any of us (or any Doc haters, I know there's plenty across the NBA-universe) had dinner with the dude, we'd walk away thinking this guy's awesome. The man has charisma.
I also think George Karl was similar, Isiah Thomas, Steve Kerr too. Whereas guy's like Joe Mazzulla or Rick Carlisle, it takes another basketball mind to want to hire them.