Zatopek was Czech, not Finnish you imbecile.
The real privileged runners were the likes of Aouita, Morceli, El G, who wouldn't even have been world class runners let alone legends if it wasn't for the fact they were born in a region with no sense of fair play and at a time in which EPO was available with no testing for it.
Morceli's older brother is about the North African natural talent limit, although I'm sure he was likely on roids and the occasional blood doping to run 3:35.
Peter Snell would run to and from work as training. He retired at the peak of his powers (not counting that 'farewell tour' of the USA in 65). He would have won a third successive 800 gold at Mexico if he had carried on, and on that new track likely run low 1:43 in doing so.
It's a myth that this era was weak. Weak in the sense that they didn't have juiced to the eyeballs Africans to compete with, that's true, but strong in the sense that participation levels from elite sportsmen in those days was through the roof in the West. Snell could have been a great tennis player. I doubt if any young Westerner would choose track over tennis today. He became a world class orienteerer after his retirement, then a world class table tennis player in his age group.
Every schoolboy knew who the best miler in the world was back then. Today, you could ask 100 Brits who the best 1500m runner is and maybe 1 or 2 would know who potato Tim is. In the USA it would be less than 1%.
And it's largely due to Moroccan/Kenyan/Ethiopian cheating since the late 80's.