My wife has had numerous papers rejected because the reviewer belonged to a competing lab. Took a few tries and a request to exclude a certain reviewer and hey presto! published!
Hard to say but my impression is that most academics are honest and would try not to do this, but also there are rivalries between labs and that tends to encourage "everything they do is bad and we're great" mentalities so it's definitely not surprising.
Yeah, the scientific review process is extremely weird. I've had several papers published and the responses you get from reviews is sometimes complete nonsense. Sometimes it feels like some reviewers do little more than skim your paper or get a power trip off of rejecting people. Lots of politics and people trying to reject ideas that are counter to the ones their own labs are pushing. I don't blame the authors for expecting to get push back from their work, many breakthroughs are usually met with resistance from the status quo.