First person evidence obviously does exist (unless I'm responding to a philosophical zombie), the problem is that it is cannot be verified by an outside observer. I suppose you could say that something only becomes evidence when externally verified, but my response to that is that you have no way of knowing if that external verification is real or just a figment of your imagination, so that external verification doesn't really get you anywhere.
You could very be a philosophical zombie yourself, just one programmed by evolution to experience consciousness. That's the argument as far as I understand it.
But that is self evident. The problem is that it doesent lead us anywhere.
Ok, so where does Dennett's view lead that is in anyway more interesting?!
Animal rights. Machine rights.
for starters if consciousness is an illusion then free will as we normally think of it is which makes our entire legal system out of touch with what we can actually blame others for.