I think 1-on-1 tutoring is great and I agree that there should be more of it. But whether "genius" has declined seems unclear to me. In my life I've personally met a handful of astoundingly smart intellectuals who work across multiple disciplines -- I imagine these people are probably as smart as the geniuses of history. And I think there are still intellectuals and artists who impact the world at large in a big way. Imo what has changed is only that for some reason these people aren't canonized as "geniuses".
I suspect that, like "top college", people are only considered a "genius" if everyone (or at least "every notable intellectual") knows about them, and there is only room in people's memories for several such people; but over time, the number of really smart people doing revolutionary work at any given time has grown from a handful to many thousands. As the ratio of "available genius spots" to "people who should be considered geniuses" has shrunk from near 1.0 in the distant past to a tiny fraction today, culture responded by giving up on canonizing geniuses.
I suspect that, like "top college", people are only considered a "genius" if everyone (or at least "every notable intellectual") knows about them, and there is only room in people's memories for several such people; but over time, the number of really smart people doing revolutionary work at any given time has grown from a handful to many thousands. As the ratio of "available genius spots" to "people who should be considered geniuses" has shrunk from near 1.0 in the distant past to a tiny fraction today, culture responded by giving up on canonizing geniuses.