I imagine because it reads like one of those "Big Medicine won't let you have access to stuff that works!" conspiracy theories, and also that it won't actually foster new brain cell growth.
It's ashame stuff gets strawmanned like that. It's not like there's a secret cabal restricting access. It's just there are many things with limited research because there's no money in it. Both the meds in the article and the lions mane studies show promising results in rats/mice. Anyone can guess which one will get more money because one is patentable and the other is not.
A lot/most of the neural regeneration drugs are still very much on patent, and very very very expensive, and a lot of insurance doesn't cover them.
While there may be some conspiracy stuff there, "big medicine" saying you need to pay $20k/yr out of pocket for something will definitely lead people to find alternatives.