Real life rock crawlers use gas engine, the throttle can only control the amount of air going into the engine. This means, at any given RPM, varying the throttle merely controls the torque. For an on-road car, this throttle response gives the driver a 'linear' feeling. Worth noting here, if you keep a constant torque, the car will want to accelerate at a steady rate until it reaches maximum designed speed.
RC ESCs, in my limited understanding merely uses a voltage control. This means if you give the ESC a 10% throttle, it will want to instantly 'rush' to 10% Max RPM. Of course, change of speed does not happen in a spilt of a second, it has to take time to slowly ramp up the RPM. It is such a poor design, because the motor amp will surge to ~ 100A ( or even higher if you pay premium to get good lipo) before the car accelerates to the desired RPM ( that is, 10% of maximum RPM). The only ESC I know that can have similar 'linear' feeling is the castle mamba/sidewinder ESC, but you have to set up 'torque limit'. However, the RC ESC cannot really control the RPM, when the load increases, the RPM will reduce, and motor current will increase, thus torque will increase.
Depending on the purpose of driving, we are merely programming the car to behave in a way consistent with the driver's expectation. Torque control gives linear feeling and fit better with on-road racing. RPM control means the motor will try its best to stick to a given RPM, therefore, the motor current will vary depending on the load. Crawlers get best traction when the tire slightly lose the grip (10% slip rate), therefore RPM control is ideal. You can google lexus SUVs has some crawl control feature. Some Land Rover also has downhill assist, which is simply an RPM control (a constant wheel speed) when the car goes downhill. The bottom line is, for crawler, RPM control is the ideal solution.
With all that being said, the biggest advantage of this AXE system seems to be its ability to fixate to a certain RPM. I think what matters is how the car crawls. I think AXE system is a big stepforward