"the largest market" always reminds me of "Bin Ladens right hand". Obviously the next one becomes the largest, but nevertheless it's like they kill at least one of those markets a month. Probably legalizing weed would stop most of that more effectively than all those police operations after month of preparation.
I think weed is by far the most popular drug on all Darknetmarkets
Weed is extremely difficult to send by mail, relative to most other drugs. It's large in volume, and it produces a distinct smell. You can combat that, but it's a pain, and I'm not sure how effective it is.
Compared to something like LSD, which you could easily slip into the pages of a book, and produces no recognizable smell. At least on the human spectrum, and I severely doubt drug dogs can smell it.