What's distinctly lacking in this piece is a definition of a genius.
This article seems to define it to be an individual that is globally lauded for their scientific/artistic achievements.
I'm sure there is a plethora of reasons why this doesn't happen anymore, it seems to me that this is a good thing, but it's no reason to conclude that we don't have intelligent people anymore.
Genius is counterfactual:
"If this person did not exist, this thing wouldn't have been discovered or created."
Impossible to prove after the fact considering that in order for their discovery to be recognized, it has to be understood and somewhat built upon the ideas that are accepted today.
I'm sure there is a plethora of reasons why this doesn't happen anymore, it seems to me that this is a good thing, but it's no reason to conclude that we don't have intelligent people anymore.