that they felt like they couldn't get anything done. This is said a LOT. The best exit interviews say something like, "I think I could have been better at organizing my plans and maybe I didn't present them in the best way, but it seemed like x person would just be a blockade everytime I would try to do that through delaying or not giving enough resources.". The bad exit interviews say, "X person just didn't let me ever do anything innovative".
Again, the best do the former. And if you don't see the difference in a person that does one or the other and why you want to work with the former I don't know what to tell you.