Plumbers are specialists, not polymaths
They have toilet unclogging intelligence

"Physicists" and "engineers" who refuse to unclog toilets and don't care about impressing their boss with a job well done aren't smarter than them, they're just neurotic and unspecialized.

They're only smart in school
>this is what people arguing that bloodhounds are not insanely dumb compared to ACDs sound like
they're smart everywhere even if they just don't enjoy repetitive tasks and prostration

This is a lesson in the necessity of retards. Who else would dig ditches and sort garbage? A society with an average IQ in the 120s would be nonfunctional without extensive automation and infrastructure already in place. But don't confuse the dedication of the retarded for intelligence or slap a "purpose" cope on to make beta minuses smart in their own way.