I believe that we are seeing the tail-end of the "Golden Age".
I think Indurain was one of the pioneers of sophisticated doping, and we have been seeing the evolution since.
I personally know a handful of racers from the late 70's to early 80's...and they tell me without exception that drugs were used. Typically "speed", or a similar acting agent would be used. In the scheme of things...so what.
Eddy was called the "Cannibal", a tribute to his tactics, not his body.
Indurain was the first rider that I can recall that was branded for his superior "genetics". Ever since, the Peloton has been aquiring "Super Humans" by the score.
We can follow the trail with race results, from Indurain forward.
The flood of propaganda to mask doping has kept up with the chemicals.
The standard tactic is some explanation involving genetics, but the more elaborate involve the "access" spectrum. For example, why is the published (PR dept.) cost of an oxygen "tent" severely inflated? Why is it even mentioned? It is used to further isolate the wealthy professional, and justify performance. The rider wins because he has access to a very expensive tent etc. This is just one tactic of the propagandist.