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On the Surface Left by an Edge
A surface left by a sharpened edge and a surface left by an abrasive are not the same surface at a finer or coarser degree. They are different in kind, and no progression of grits converts one into the other.
The difference is what happens to the fibres. A plane or a scraper severs them cleanly and leaves their cut ends flat and reflective, so light returns from the surface in an even sheet. An abrasive tears them, leaving a layer of bent and broken fibre ends that scatter light instead of returning it. Going to a finer grit makes the scratches smaller but does not undo the tearing; it simply produces a more uniform haze.
This is most visible once a finish goes on. A planed surface takes oil or shellac and appears to gain depth, because the light is travelling into the timber and coming back. A sanded surface of the same wood, given the same finish, looks flatter and slightly grey, and the reason is the torn layer sitting between the finish and the wood proper.
It shows up even more sharply where a surface has been worked both ways, which happens constantly in repair and in any piece where a scraper was used on the figured parts and abrasive elsewhere. Under a clear finish the boundary is obvious, and it is obvious as a change in reflectivity rather than a change in colour, which is why it cannot be corrected by adjusting the stain.
The practical position is not that abrasives should be avoided. They are the right answer on end grain, on curves, on anything already contaminated, and on figured timber that will tear under any blade. The position is that the two treatments should not be mixed on surfaces that will be seen together under the same finish, and that where a blade can leave the final surface, it usually should.