I think this also sums up his weakness though in a megacorp like Meta. He's technically brilliant, and that can go a very long way. But in a large corporation, technical brilliance is secondary to excellence in leadership.

I remember reading an article in the '00s or '90s about how Id worked, and it just seemed not very scalable beyond Carmack.

And while he his companies have had great success, other '90s era peers - Valve and Epic - are on a whole other level today. Technical brilliance brought his company far, but it can't bring you to those heights.