Argumentum ad populem holds an opinion to be true just because the majority hold it (regardless of WHY they hold it)
Peer review, at least in the ideal, consists of experts examining the methodology and reasoning of a paper,possibly suggesting revisions and the editors of the journal making a decision based on the reviews. A paper which fails to pass peer review can be edited or even submitted unchanged to another journal.
I really don't see that much in common between the two.