Your original premise is too faulty to reach any kind of conclusion.
There are thousands of brilliant photographers shooting today in digital and analog. The difference is everyone is bombarded with images today that nothing seems special.
If you're trying to compare the so called greats of yesteryear, they were greats because there were so few (in comparison to today) of them shooting and their work seemed special and unique. You can also add in the nostalgia factor to their work. In the 1950's great photography was only seen in magazines like Life, National Geographic and a few others, and even then there was only something spectacular every few months. TV sucked so the images were not impressive. Occasionally a local newspaper had a great photo, but not often.
Add in the fact that people didn't travel, so a great photographs would open up whole new worlds to the viewer. Today, people have literally seen everything. We are jaded.
Your original premise is wrong. There a people on APUG that are better than Ansel Adams. There are probably better street shooters than HCB. There are better portrait photographers than Karsh. The only difference is, nothing is special anymore.
And this has nothing to do with analog or digital. And motor drives have been around since the 70s.