I've not seen this yet, but it's probably people trying to chase that one achievement to stay alive in a game for 60 minutes (which shouldn't be an achievement imo).
At the end I think the circle does get pretty small, it could probably get a bit smaller but at a certain point it'd be too in favor of planes with the best brakes and cornering. Also unlike land based battle royal shooters if the circle gets too small it'd be impossible to have a dogfight without it being a game of who can fly tighter circles without getting eaten alive by out of zone.
That said, I do agree the zone behavior could use some kind of improvement to make the match progression smoother.
I have seen this a lot and I understand the frustration. But even though they try and nascar around the circle take the opportunity to practice your aim since they are not willing to fight back. Sadly there are players like this but that’s just another aspect of the game. I fly on intermediate and refuse to use chase camera as it doesn’t truly lead targets that well.