The last paper I published came back with 4 reviews comments:
review 1: This is important for the field, fix x, y and z and it should be ready to publish
review 2: This adds absolutely nothing, they are missing references from research group a, research group a, research group a.
review 3: Looks good, fix a, b, and c, and add references to research group b, research group b, research group b.
review 4: looks good, but figure x doesn't seem to show what you say it does, fix it or the caption.
From there it was actually fairly simple to see who was reviewing based on which papers they said we were missing. With research group A in particular, they were working on similar stuff so we think we may have scooped them. But that's also a bit of the problem with reviews, subject matter experts are probably also doing similar research. And if they have a big ego it can potentially hamper work by other groups getting published.