> If you find good matches but not great matches, you stick around.

I dunno, I have difficulty seeing how the dating sites could singlehandedly pull that off in the average case without the site users really leaning in to help. It would seem to run into the basic reality that men and women historically pick the best match from a fairly small pool of people. A dating sites can't do worse than that even if they're trying. If people are willing to use the same standards as all their ancestors then they'd pair off quickly.

It seems more likely that there is just a natural dead-sea effect because of that where the people on the sites over the long term are not the sort of people you'd settle down with, and there is also this subtle idea that the dating site is there to find someone a perfect match (probably doesn't exist to start with). Those are design issues that go a lot deeper than any algorithm the sites might be using.