John Lucas
Steve The way Stewart Batty teaches the negative rake scraper it is 2 things. The negative rake, which as you say is simply lifing the handle, and the sharpness. There is also another function. Then angle of the body of the scraper.
I have been playing with this and there is a difference between holding the handle high thereby creating a negative rake to the upper surface of the scraper, and holding the handle level with a negative rake ground on the top. The difference is the force applied to the turning by the cutting edge. With the true negative rake scraper there is very little force applied to the turning. The tool rest supports the tool and lets you be very gentle with good control. If you hold a regular scraper higher it is tilted on the tool rest and there is a more pushing action against the wood because of the angle of the tool on the tool rest which is downhill.
When you combine the purposely negative rake ground scraper with a grind that is 45 degrees or so included angle you get a very clean cutting tool.
I hope that explained it well enough.