The author concludes that under the current system, licensed physicians cannot recommend the medicinal use of herbs.

Why?

Because in order for a drug to be offered for sale, it must have regulatory-agency approval for medicinal use in specific illnesses/conditions.

Getting regulatory-agency approval for a drug is so expensive that one must be the holder of a patent to recover the cost of getting the approval.

Herbs and their medicinal uses cannot be patented.

The author assumes if one cannot recover the cost of getting regulatory-agency approval for a drug, then the drug won’t get regulatory-agency approval. (This overlooks the possibility that someone or some group might still get regulatory-approval despite the inability to recover the cost.)

The author also assumes that if a drug can’t be offered for sale, then licensed physicians cannot recommend its use. (This overlooks the possibility that licensed physicians could still recommend illegal drugs.)