Multiple registrations are being filed for the same person in order to game the system. This is discussed in some details in a USCIS report [1]. The increased application fee is presumably to stem that practice.

https://www.uscis.gov/working-in-the-united-states/temporary...

Honestly, with a much higher minimum salary I don't see a reason why the cap couldn't simply be eliminated removing the need to play such games.