Disagree; basically the steroid era brought the times down significantly, something like the difference between the 80s and 90s in BB.
Jim Hines ran a 10.03 on clay in 1964.
Asafa Powell runs a 9.74 on rubber surface in 2007, with better shoes.
That's 29/100 in 43 years.
Of course the steroids have brought the times down. But the training these sprinters are doing is most likely still very far from being optimal.
If anything, the steroids have prevented the training techniques from developing, since the times went down anyway.