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

You could write a book on why it's practically impossible to create a new OS these days. Love Carmack for stating it so clearly. I also love that called out TempleOS, I also have a weird respect for it. Plan 9 is the probably the best example of a totally new OS and I hope someday it becomes viable because it's really a joy to use.

But ultimately it just makes sense to adapt existing kernels / OS (say, arch) and adapt it to your needs. It can be hair wrenchingly frustrating, and requires the company to be willing to upstream changes and it still takes years, but the alternative is decades, because what sounds good and well designed on paper just melts when it hits the real world, and linux has already gone through those decades of pain.

OS isnt the hard part.

The driver ecosystem is the moat. Linux finally overcame it decades later

Yeah, the Linux kernel has ~12m lines of code. <1m are the core, the rest are drivers.