I actually have met a dermpath guy doing Mohs. It is not common, but it happens. But most Dermpaths makes enough money to put their licenses at risk to try to perform Mohs surgery on Medicare patients only. Private insurances won't allow a dermpath to be on the panel as a Mohn surgeon or a dermatologist.
With an unlimited medical license, you can do open heart surgery if a hospital credential you and if you can get patients or insurance companies to pay you. The only thing that stops plastics or ENTs doing Mohs in United States is the CLIA number. Without a CLIA number, only insurances won't pay you, it is illegal to perform Mohs without a CLIA certified lab.
However, outside of the United States, ENT and plastics do Mohs all the time and they train others. I know there are many plastic surgeons doing lots of Mohs surgeries in Australia. Thanks to CLIA we have enjoyed tremendous turf protection in the United States as Mohs surgeons.