From the perspective of someone who doesn't have an 'ear' for music (but has other creative talents), it's somewhat niave to assume an artistic work is somehow enriched when only one person's hands are on it. That's not to say that there aren't brilliant people out there capable of creative masterpieces without any external input. Rather, comments, criticisms, and advise from others oftentimes can become a stimulating source of inspiration, allowing you to get from point A to point B when you would otherwise be stuck at point A.
And believe me, when you can't get from A to B no matter what you try, it's a very stressful, head-banging experience. And I don't mean

, I mean :aargh:
Jam it back in, in the dark.