Nothing stops the forward march of any creative endeavor like the need to do it absolutely perfectly. And who is to judge what is 'perfect' anyway? What I have judged full of flaws so many others have called terrific. Maybe the definition of Perfection is something that actually gets done.
It certainly helps, I think, with some actors to understand the process of acting. You see what extraordinary pressure they're under, there's a huge circus dedicated to a particular moment and they're got to deliver and it can help that you, even if empathetically alone, understand what they're doing.