I don't consider myself a great writer by any means but it does take a lot of effort for me to write.
Some hubbers tell me that they can whip up an article in 15-30 minutes. For me, it usually takes a week.
I don't believe that I am a perfectionist but I have high standards about what I want to write. If I don't meet those standards, I don't publish.
So, over all, I would say that perfectionism (or in my case, high standards) greatly helps the quality of my writing even as it reduces the quantity.
That's fine with me.