If it's ever revealed that app reviewers have rejection quotas or some other bullshit internal metric that is driving this I would be the least surprised
Internal metrics, yes. If another reviewer finds an issue in an app that you reviewed, then you get your score docked, so reviewers have an incentive to whine about everything, since there's no penalty for bringing up issues that aren't actually issues and wasting everyone's time.
Is this speculation, or do you have insider knowledge?