Well, yeah, but learning to review is less difficult than learning how to communicate clearly, crisply, and forcefully. So in a well administered review, most benefits accrue to the authors even if the reviews are poorly done, so long as they are ethical. (Editors can step in when reviewers are being unreasonable or ignoring explicit instructions; unfortunately professional editors at glam journals can also step in to push exciting or politically expedient work into press before there is time to adequately vet it, which sucks and gives everyone a bad name).