According to these news articles.

direct-to-consumer advertising (DTC ads) of drugs through TV, Internet, and other media channels is an about $5B big waste of money. DTC ads, the study finds out, is based on scant data that has a small effect on the sales of drugs.

Prescription drugs are not like selling aspirin, cereal, or popcorn.

Stephen Soumerai, head of the research group that worked on the study thinks DTC advertising has failed because the process of buying prescription drugs is not like buying over-the-counter medication.

According to Soumerai, a person has to see an ad, get motivated, contact their doctor, show up for an appointment, communicate both the condition and the drug, convince the doctor to prescribe it, and then actually fill the prescription, which is also likely to carry an out-of-pocket cost.

It is certainly not a waste for modern snakeoil sellers (marketers, spammers, and scammers) that eat from the $5B pie. Same pattern as usual: theories made out of thin air and scant data.

I will not be surprise if they soon send a paid researcher or someone with vested interests to write a rebuttal.