"proof" was an unfortunate phrase to use. However, a proper statistical analysis can be objective. And these kinds of tools are perfectly suited to such an analysis.
From what I remember, (long before generative AI) you would still occasionally get very crappy reviews (as author). When I participated (couple of times) to review committees, when there was a high variance between reviews the crappy reviews were rather easy to spot and eliminate.
Now it's not bad to detect crappy (or AI) reviews, but I wonder if it would change much the end result compared to other potential interventions.
Without proof there is no confirmation.