Wiremold, and like products, are not considered to be a "wiring method." Rather, they are considered as a complete assembly to be an "appliance." A glorified extension cord or power strip, if you will, but one suitable for permanent mounting.
If you wonder how Wiremold can ignore box-fill rules, this is why,
I see, it's because I need to add one more circuit to my existing panel. The apartment is not mine, so I need to do it in a way where I'm not fishing through walls (that much) and tearing walls out to mount boxes and run conduit. So, I believe wiremold is the easiest way for me, since the run is only going to be about 7ft of mold, 2 #12 conductors, and a #12 grounding conductor for a 120v, 15A, single receptacle to power a secondary refrigerator.
Question, would the proper way to feed a dedicated circuit through a wiremold raceway be to have a NM single gang box, mounted inside the wall, of course to a stud, then feed the circuit through there to a wiremold single gang NM box mounted above it (to be flushed with the wall surface) acting like a junction box and connect the wiremold raceway from there?