[indubitably]

It's also releveant that the author feels perfectly justified in making recourse to a hypothesis about history which far from easy to test: “The idea of genius elaborated during the Romantic Age (late 18th and 19th centuries) has done harm to education.”

Compared to what? Clearly he doesn’t know how to make a historical argument — perhaps he considers such arguments beneath him.

[sn9]

That's a rather unreasonable criticism. I'm sure if you could ask the author (before he died a few years ago), he could provide you with more detail.

Requiring an author to expand on every question a piece brings to the readers' mind is just an unreasonably high bar.