> Healthy, recreationally active but untrained young males

Yeah this is why. Anything you do as an untrained person is going to get you newbie gains. It's just really easy to improve initially. Doesn't mean it'll work after the first 6 months

Perhaps there's some unmeasured influence, but this study was looking only at the difference between growth within subjects vs between subjects. If the subjects were all "newbies", then that doesn't explain the results.

They're essentially saying that individual genetics explain the majority of the variation seen as a response to muscle stimulus in their test subjects, not the mass used, because the variation within the test cohorts was greater than the variation between them. You can argue that, if they didn't test experienced lifters, the results might be different in that population, but you can't dismiss the results on those grounds.

exactly. when you're new, virtually any type of lifting you do is going to create sufficient stimulus to trigger maximum muscle growth, because you're going from 0 to 1. unfortunately, since the only people that researchers can usually convince to participate in their studies are untrained, this has led to an enormous amount of junk studies where they try to extrapolate the results to people who are not untrained.

this wasn't a study of absolute growth (sure - newbie gains), but rather the difference between high and low load programming within individuals.