ABS is a very human-centric system the tries to keep the car controllable under low traction, often by sacrificing something aspect of movement. The neural nets here throw all that out of the window, and control the car with direct physics, without being once or twice removed from reality.
The video also has some very interesting points about how the AI should be able to control the acceleration and braking on each wheel individually - so we really don't need to limit AI driving with human safety or control systems.
That, and also ABS only prevents the wheels from locking (much) under braking. It doesn't help you if you enter a corner too fast, or hit a patch of ice, or stab the throttle too early on exit, etc. Traction control helps with the last of those scenarios, and modern stability control can start to help with others. But as you said, this system would theoretically be able to go straight to the most effective inputs in any given situation, since it doesn't have to deal with a human driver in the loop.
This was what finally killed my long-held attitude of "we don't need no stinkin' ABS". No matter how good I am, I will never be able to independently limit-brake each wheel of my car.
Same on gravel, and for the same reason. Neither of those are something I run into particularly often, though. Painted lines on wet roads that will cause the wheels on one side to lock up, though...
The video also has some very interesting points about how the AI should be able to control the acceleration and braking on each wheel individually - so we really don't need to limit AI driving with human safety or control systems.