Yes, there is a wholly different educational quality from one-on-one tutoring compared to mass produced standardized 20+ on 1 textbook curricular politicized 'education'.
However there are other areas that I suspect have a hand in any broad genius decline.
I would look to declining nutritional quality, for a number of reasons:
* depleted soil
* pesticide residue
* fertiliser residue
* contaminated water
* dodgy preservatives
* corn and sugar subsidies
* poorly understood food additives
* selection for looks over nutritional quality
* ocean pollution - mercury in fish, for example
* Over-processing
There's environmental factors to consider:
* air pollution
* water pollution
* forever chemicals
* lingering lead and the like
* noise pollution
* distractions - ie; porn, gaming, porn, movies, porn, TV, tinder, phones, porn, etc.
Cultural and societal factors:
* All the money is in the worst shit. Math whizzes become quants, or help out big data. Artistic geniuses become marketing and advertising shitlords. Storytellers get churned up into the latest mega franchise, or become formulaic parodies of themselves to satisfy publishers.
* Lack of holistic thinking. Specialization is strongly emphasized in many ways.
* Fierce and relentless, scientifically designed, soul-crushing propaganda, twisting hearts and minds into a constant state of fear.
* Politicized and weaponized anti-intellectualism.
* Scientism
* Media priorities
All that said, I think figuring out how to make tutoring better and more wide-spread is our way out of a lot of this stuff... Which is probably why it will be viciously attacked by the usual profiteers and their paid defenders of the status quo.