I think the perfection comes into play when a Dom/me realizes their humanity. That's just it, they are human and you can only strive to be perfect. Does it mean you are or will be? No. But the fact that the subs see the changes the Dom/me makes for/because of them, it does wonders for a relationship.
If you happen to be a newbie sometimes it's still nice to see how much your Dom/me does and is willing to do for you as a sub. Many play Dom/mes do see subs as either an easy lay...a target so to speak for their own selfish ends. Not saying good Dom/mes aren't selfish, after all why would they want/need a sub if they weren't in some way. But the key part is that the play dom/mes will break the will and often heart of a submissive. Making someone 'worthless' in their own eyes is a breaking of the human spirit, and I've seen and heard of it happening.
These are the cases, which I believe Ashton pointed out, in which a sub will blame themselves for it not being perfect. Submissive doesn't mean stupid, but so many subs come in expecting that they can not even make suggestions or "stand up" intellectually to their Masters (masters as the case may be) that the first time one does it they instantly expect to be dropped to the side like yesterday's newspaper.
I think in the relationship realm it's a give and take. The Dom/me gives the submissive everything they need in order to 1. remain as a submissive 2. desire to be a submissive 3. wish to earn their place as that Dom/me's sub. While in direct relation to that a submissive gives their Dom/me 1. servitude 2.loyalty (a sub is a friend/listener/wall to bounce things off of) 3. companionship. My Sir smiles in a way...I've never seen many smile when He reaches down His hand to stroke me. I could have been quiet for minutes (hours is stretching it for me) but the fact that He knows I'm there and I will be there, is a release for Him.
To me D/s and BDSM isn't just about how well He hits me or how many times I get off from spanking or how many times Sir gets head/orgasms or whatever He demands. It's about trust...when you know someone well enough, trust them enough, and love them in the way that often we come to love our Dom/mes then that relationship is perfect.