"It's undoubtedly one, but in it's evaluation how do you separate people that voted and liked the post from people who merely voted for the curation rewards?"
I'm afraid you can't, at present. I've been posting a series on suggestions to improve curation to break that link. Until we change that formula, it's going to keep happening.
"Or, like Jerry, do you think that popularity = quality?"
Popularity and quality may be different things, but the formula for financial reward is not:
Quality = Reward
it's:
Quality * Reach = Reward.
You may appreciate this post, despite disliking the facts as they are: