Patrick Chase
Those "teeth" are actually flat cylindrical projections, each with many individual diamonds lined up in the same plane. It's therefore an "interrupted flat" surface rather than a toothed" surface.

The theory is that the gaps between those cylinders channel away swarf and lubricant, which is a very common design approach in diamond abrasives. Because the edges of the cylinders don't "cut" they don't leave marks as a rasp would.

Some other examples of the same basic approach:

DMT DuoSharp: https://www.dmtsharp.com/sharpeners/bench-stones/duosharp/

3M Flexible Diamond Tape: https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Flexible-Diamond-Hand-File-6210J/?N=5002385+3293082566&rt=rud

Diaface Moonflex files (popular with ski tuners): https://www.amazon.com/Diaface-Moonflex-Diamond-Stone-70/dp/B01N8V1NGV