IMO, Rage was a poorly executed game, and the way they handled their own failures (blaming drivers and such instead of their own mistakes) made it only worse. His excuse was that he used a "beta driver adapted for the game" ; the Windows-certified drivers weren't good enough?
I always make sure I have the latest drivers installed before blaming anyone else for glitches, but this was a bit too much. A serious developer can not ask users to switch from certified, stable releases to a beta, potentially unstable driver just to play a game.
And, guess what? People that did that did not report any major improvement in rendering, either. Carmack never admitted that it was a bug-ridden release, but TBH the only "beta" here was the game itself.
I used to respect him a lot back in the Quake days; not anymore.