Markets are imperfect and irrational, but you really don't think that there is a trillion dollar misunderstanding about the efficacy of the practice? Idk jack about advertising but it seems unlikely to me.
That's fair but homepathic medicine is dwarfed by regular medicine in the industrialized world. There's no homepathic Pfizer or Bayer. I think if there was another practice that was way better than targeted advertising, targeted advertising might exist as a distant woo-woo second.
Just the fact that people buy ad campaigns doesn't mean that they have any effect at all.