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I may be wrong about that. I just know that hard stones are preferred for keeping plane & chisel backs flattened. Sigmas & Shaptons do that well.

Slightly softer stones are good for J/Knives as...

The Shaptons were designed to cut hard tool steels & they do cut very deeply so you can get microchipping on razors. Light pressure is crucial when using them.
The Chosera 1k is loaded with abrasive...

Grit size doesn't equate to abrasiveness. It's a much bigger rabbit hole. Lots to consider. Friability, particle shape, binder, to mention a few factors.