Yes, I'm also against fake natties telling people who's possible on Youtube. The supplement industry is incredibly corrupt. In fact, responsible use of steroids far from the worst. Dorian Yates is still healthy after all these years. The worst are people who who put toxic compounds like superdrol and amphetamine into supplements without the consumer's knowledge. Not only that, most whey proteins on the market are fakes that contain far less protein than they claim and even toxic fillers.
I would mostly agree your sentiment that Nate Diaz is about the peak of natural athleticism... but I would say that he's not natural, because he's a paid athlete... he's taking some sort of PEDs... yet I would also say that it's actually possible to get maybe 5-10lbs bigger than him naturally if you train for size rather than performance. My examples of natural limit would be Frank Yang and Omar Isuf.
This video is an excellent explanation... It's just mass, but a certain 3D look, and even smell, behavioral mood, performance level, speed of transformation, consistency of look, etc.
RE: Are women attracted by muscular male bodies? (Part 1.5 of 2)