You are right that there is nothing sacred or absolute about the "ear" or voicing of the manufacturer. Theoretically, anyone should be able to tune a piece of gear to their own liking.
Instead, we tend to buy different pieces from different manufacturers until we find one whose "ear" matches our "ear". To some extent, we are always paying for the "ear" of a particular manufacturer, and we risk losing that when we mod.
Chris has tried to emulate the sound of a good MC phono cartridge, to get a very analogue sound. We are paying for his "ear" and experience in achieving that end.