The Insider program was initially created to combat leaks by just making every build public. At first they really listened to feedback when Gabriel Aul led the program - after he left, it became a joke (they tried hard to make "ninja cat" a thing) and the "unloved child". Microsoft doesn't know what to do with it, testers can't test anything and provide feedback since 1) MS ignores it 2) it has a literal roulette built in where features get (de-)activated upon reboot. They reopened the beta program for Windows 10 a year ago (to backport some Windows 11 features like Copilot?) and closed it after a few months.