Sometimes reviewers also look for whether the paper cites enough of their own papers, who is publishing it (regardless of whether the review is supposed to be anonymous or not), whether it clashes with a paper they're about to publish... science is just as full of politics and corruption (if not more) as any other field.
I almost added "place the research into the context of other relevant research" as another way of saying "cite enough of the peer reviewer's papers" but fair enough.
I'm not sure if science has as much corruption as other fields, but it definitely has politics. PIs get to their position without the typical selection process for leadership that happens in most larger orgs, so there's more fragile and explosive personalities than I find in other management/leadership positions.
