i've realized that people are quick to tell others "x is the MOST important thing" for success, where x is the thing they, in particular, struggled with the most.
the reality is that anything can hold you back: drugs, lifting, diet, even stupid tiny things like where you place the bar on your clavicles, what sort of shoes you wear, etc.
there's always a bottleneck. you address the "bottleneck factor" (say that means eating enough carbs or protein or whatever), then something else becomes the bottleneck (maybe tucking your elbows on bench), then you fix that, and the bottleneck moves somewhere else. eventually you end up either thinking you know it all (ignorant of the bottleneck) or simply unwilling to address it (e.g. wanting to stay natural, not willing to put time in to the gym, not willing to fix the diet, etc.).
anyway, the point is, no one factor is inherently any more important than any other. for example, it's popular to say "all drugs". well, for someone who blasts all the drugs in the world but eats 0 calories per day, food will obviously be their bottleneck. once they start eating, they could very well turn around and say, "All drugs? Nah, ALL FOOD BRO."
Anyway, you can usually tell what someone struggled most with by listening to what they claim to be most important. In all likelihood, they probably went years without realizing it was their bottleneck, only to finally see results once they addressed it. Might be useful information for you, or might be worthless -- perhaps your bottleneck lies elsewhere.
