This is an opinion: Wood is an organic material that NEVER cuts the same from stock to stock. Therefore a full depth checkering machine would become a liability instead of an asset. It is hard enough to not dig ditches with my MMC tool (after 23 years of checkering) on some stocks without NOT being able to go at it slowly down to depth.
I did not say that the tool needs to cut full depth in a single pass. I merely indicated that a rotary tool is incapable of making a full depth cut to the border; the radius of the cutter prevents that. One must finish the cut with a hand tool, and that takes a lot of time. A straight line tool, or a reciprocal tool with a large cutter radius would be capable of making a full depth cut right to the border, whereas a buzz-saw cutter wouldn't.
