Technology has certainly evolved to make new bikes much more competitive in smaller form factor to vintage larger bikes. But do not discount how much young riders have developed too. They can train on simulators contstantly (even as 10yo at home with PS4 etc) and their athleticism can also be more finely tuned. Time teaches if you choose to learn from it. And I’d expect that today’s athletes are far more fit, limber, and suitably strong in their respective critical areas than yesteryear’s riders were.
There is no discounting talent of course, but hard work beats talent when talents stops working hard. Plenty of examples of that in Pro Sports across all fields. And todays young guns are hungry, motivated, and very well-funded to excel.