You're spot on, except you're not as cynical and bitter.
As Joseph Campbell once observed, civilizations are a collection of myths which everyone in the society accepts/believes. We were raised thinking that science worked like Star Trek, and that blinding genius was what made for great scientific breakthroughs. But what is "accepted" scientific fact? Its basically well designed, reproducible experiments that demonstrate the validity of a theory which is eventually accepted BY a body of academic peers supposedly trained to conduct and recognize that standards were met and valid. Guess what? No body of peers (mediocrities), no scientific validation.
Science always was, and particularly today, a relentless, and excruciating labor of many millions of ants, making progress by each crumb of discovered knowledge. It is a social hive that eventually culminates in something significant and new. When it does, its the queen that gets all the credit, even though she spent all her time popping out worker drones. You cannot even hope to get credit in the science/history books unless you happened to be at the top of the pile at the time, with powerful friends to validate you as the "discoverer".
What made "great" scientists recognized, in the previous century, was not mere genius or relentless work or even showmanship. The only ones that were noticed were the ones who realized the great collection of authorities in the field were dead wrong, and then had the guts and genius to prove they were wrong. They were cowboys like Einstein and Tesla. The days of the cowboys are gone. (And forget about working in a patent office part-time, while working on your breakthrough discovery. Then again, the pay and financial security of academicians/researchers are so bad, the next vanguard of scientists just may require a day job.)
The last scientist I can think of who went maverick and made her mark was Barbara McClintock. She had to stand by her research for decades while it was dismissed by her peers, until they couldn't continue to look stupid and wrong. And who the hell here even knew who she was when I mentioned her? Think of all the people who died in the previous decades from peptic ulcers until an internist conclusively demonstrated that ulcers were induced by bacteria, and simple antibiotics would cure the condition. The bacteria theory for ulcers was around for decades, but guess what? The wrong body of peers were the deans of Internal Medicine and editors of prestigious journals at the time. There are probably many scientific discoveries unknown to us, merely because the first guy to prove it just didn't have the right juice, or some bureaucratic body had a financial interest in dismissing the findings.
Assuming the study's conclusions are valid (and I don't believe anyone should take any studies' results for granted anymore), it only demonstrates that science has become more bureaucratic in the past decades; you need to go to the right schools, know the right people, and managed to get into the right "chairs" to be in position to get "credit" for a scientific endeavor. That takes time, which explains why "older" scientists are credited later in life today. This is not a good thing. Picture being Albert Pujols and never being "allowed" to play in the World Series because he wasn't on the roster of the Yankees, Red Sox, or Braves. In our case today, we are strangling our own advancement by our own bureaucracy (or societal pedigree).