Correct. There also seems to be some sort of interaction between AAS/IGF/GH and insulin that isn't fully understood that could radically change the results for polypharmaceutical bodybuilders with hyperoptimized diets compared to what studies show in normies.
There are a plethora of good studies that demonstrate these interactions between AAS and GH, there's good data on rhIGF-I and skeletal muscle anabolism, and some studies that do demonstrate the potent skeletal muscle hypertrophy (as well as its mechanisms) induced by slin.
I'll admit the studies on combined use of rhGH & rhI (slin) are atrocious because they're mostly designed to exclude systemic administration & hyperaminoacidemia (slin use dramatically increases protein uptake and utilization) and focus on irrelevant models for our interests (I believe intentionally, to not become the "smoking gun" study showing slin's dramatic skeletal muscle anabolism).
Unfortunately, a quorum of medical professionals want to dispute slin's muscle anabolism: right now slin in the medical community is akin to AAS in the pre-Bhasin era, when it was commonly viewed as a myth that AAS were anabolic; of course, with respect to insulin, this is just as much - if not even more so - of a joke.
I would just remark that the rigors of the scientific method do tend to yield truly comprehensive understanding, not some YouTube video. In my view, the "Goldilocks zone" for understanding drug, training, and nutrition interactions is in the trenches for practical (inductive) insight with a keen eye to the literature for the empirical (deductive) insight into why something occurs. There are a lot of facets from both the practical and empirical that can influence one another.
But why do so many bodybuilders strive to characterize untrained subjects as some other species, and bodybuilders as superhuman? Are all humans not subject to the same physiology when the mechanisms are basic (fundamental) to man without respect to bodybuilding practices surrounding nutrition and training? And there are, of course, relevant studies for bodybuilders' nutritional practices as well as training practices... though, admittedly, no unified longitudinal interventional nor observational series of studies in our population showing clear dose/response of different protocols. That'd be nice, but alas, the Declaration of Helsinki is a bar to this sort of study ever being approved nor published.
I'd respond to this very common view with the expression, "Don't throw the baby out with the bathwater." Science has a lot to offer and we'd be remiss to ignore it just because [X, Y, Z gurus] have more clients that are yoked than God and because science is for fucking nerds.