It's been possible to increase growth hormone by injection for a couple decades now, and I thought there was a cancer problem[0].
Also, there's the drive for homeostasis. In my own experiments with dietary supplements, I get a short term boost due to the supplement, but the body gradually re-configures itself accordingly, so there's no long term benefit. e.g., caffeine[1]
You point to one example of homeostasis and therefore we should just give up on all medicine? That’s like someone putting down the idea of vaccination because they developed a coffee tolerance. The human body is complicated and diverse and homeostatic forces aren’t omnipresent or present at the deepest mechanistic levels.
Also, there's the drive for homeostasis. In my own experiments with dietary supplements, I get a short term boost due to the supplement, but the body gradually re-configures itself accordingly, so there's no long term benefit. e.g., caffeine[1]
[0] Growth Hormone's Links to Cancer https://pubmed.ncbi.nlm.nih.gov/30500870/
[1] Chronic Caffeine Alters the Density of Adenosine, Adrenergic, Cholinergic, GABA, and Serotonin Receptors and Calcium Channels in Mouse Brain https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3437321/
EDIT: Author has a wikipedia article and a website. https://en.wikipedia.org/wiki/Brian_Hanley_(microbiologist) https://bf-sci.com/