Their training was brutal but there are many bodybuilders who train like that. I think overall consistency in all elements is what set them apart. Those are the type of guys if they have 8 meals to eat each day they will eat those exact meals every single day. That is rare even with the best bodybuilders in the world. Chad Nicholls basically said Ronnie was a machine and would do anything he told him and never cheated on his diet (unlike other top bodybuilders). They also won't miss gym days because they live for the gym.
On top of that you have genetics. Guys almost act like Dorian didn't have good genetics at times which is nonsense. He may not have had Flex Wheeler genetics but he had genetics to be huge and ripped. Look at Dorian's calves they are ridiculous. Most guys could never have calves like that no matter how they ate or trained.
My post isn't in reply to you as I agree with you but just the many posts I see all the time about bodybuilders not training hard anymore and that's why they don't look as good. There are loads I see squatting 6-8 plates and deadlifting the same and pressing 4-5 plates and basically training brutally hard. These days due to the impact of social media all the top guys get most of their workouts filmed. There are a few exceptions but they still obviously train hard (Dexter Jackson, Phil Heath etc). Incidentally some of the middle eastern bodybuilders training today is ridiculous and even more impressive than Dorian and in some ways Ronnie too (they lift similar weights but weigh less).