That's wild. Their reasoning (or even finding, they should have the data) is that if you isolate the annoying players away from the general population, people overall play less? I'd intuitively expect the opposite, you play less if you constantly have rude players around.
Or is it more of a thing of "60% of our players like to harass people, if we only pair them with other harassers, they don't have any fun and leave"?