As a drug discovery researcher, I can tell you something that might sound crazy: many of these older drugs would have a hard time getting approved today. Some of them would never even have made it to the FDA at all.
The best example is aspirin itself. It’s one of the foundation stones of the drug industry, and it’s hard to even guess how many billions of doses of it have been taken over the last hundred years. But if you were somehow able to change history so that aspirin had never been discovered until this year, I can guarantee you that it would have died in the lab. No modern drug development organization would touch it.