I think they already had this info from months/years of weekend request shows and the weekday request hour (1-2). What seems to have happened is that they had more people listening for longer and, unless they have premium access, being exposed to more ads. The top 500 was what listeners, at least the ones who voted, wanted. I hope this doesn’t see a shift away from playing more recent bands or the country rock that they have been pilloried for. If it wasn’t for PR (I'm a listener from the very early, ad free days) I wouldn’t have heard bands like Volbeat, Those Damned Crows, Blackberry Smoke, Black Stone Cherry, Greta Van Fleet, the list goes on and I’m happy about that. It has also achieved the reverse by confirming my dislike of some bands that a lot of folk hold in high regard. It’s not all gold, but then I refuse to believe that any artist’s catalogue is all gold, no matter how revered they are.
Finally, a top whatever that has caused controversy; who would have thought that would be the outcome?