John Carmack's arguments against building a custom XR OS at Meta

I'd love a truly new OS, but I just don’t know what it would look like at this point? "New OS" ideas tend to converge on the same trunk.

Building a hobby OS taught me how little is just "software". The CPU sets the rules. Page tables exist because the MMU says so. Syscalls are privilege flips. Task switches are register loads and TLB churn. Drivers are interrupt choreography. The OS to me is just policy wrapped around fixed machinery.