1) It doesn't work. It leads to the lowest common-denominator winning.
2) Humans aren't rational.
3) The world is complicated enough that the median person simply doesn't know much about anything outside of their silo.
4) There are powerful forces conspiring to profit off of people's ignorance, rather than to turn them into less ignorant, more rational, more empathetic people, more curious people.
5) There are many people who simply aren't that curious. Left to their own devices, they will be overly susceptible to trickery and populism.
This might be a nice idea in a socially homogeneous group of a small number of like-minded farmers. It fails surely and predictably in a large group trying to make good decisions in a complex and technical world.
Read: Why Smart People Make Big Money Mistakes And How To Correct Them: Lessons From The New Science Of Behavioral Economics