I think it is pretty well documented how much of an edge the riders were gaining a decade ago...
Here is a good link:
Dr Tucker says you can see a marked difference between today and the bad old days when there were no tests for blood doping or drugs such as EPO.
“In the late 1990s and early 2000s if you were going to be competitive and win the Tour de France you would have to be able to cycle between 6.4 and 6.7 watts per kilogram at the end of a day’s stage.
“What we are seeing now, in the last three or four years, is that the speed of the front of the peloton [of] men like Bradley Wiggins, Chris Froome and Vincenzo Nibali, is about 10% down compared to that generation and now the power output at the front is about 6W/kg.”
I will have to agree with you. So how about someone like LeMond? Was he doping?