Hmm. Interesting to contemplate.
It seems possible that some buyers might opt to do that - avoid leaving feedback, certainly if it takes too much time.
But think about this: much of the reason for allowing buyers to leave feedback may be to give them an outlet to express rage or disappointment if the deal goes wrong. This in turn makes it less likely that buyers will use other avenues to express that outrage - i.e., submitting formal complaint, proceeding with a fraud charge, etc. Is feedback just an increasingly complicated placebo?