According the the person interviewed in the article, it is the plant, and the chemical itself.

Creating synthetic mescaline in a lab or growing peyote in a greenhouse is a violation of natural law, and interrupts the unique symbiotic relationship with the plant. “What western scientists call mescaline is for us the essence of the medicine,” said Jones. “It is the soul of it and what makes it holy.”

There’s definitely a branch of “Psychonauts” that want to engage in the whole ritual practice (See all these psychedelic retreats/therapies/ayauasca “experiences”), but it sounds like many of them don’t want the chemical commodified at all either.