Why is acadmic education a universal institution if intelligence is considered an individual trait?

One could always opt to go to a trade school, or apprentice themselves in a certain profession if they only wanted the skills to perform one task. Intelligence is not the same as education. Going to a university for 4 years introduces you to the great thinkers that have come before you. You become a more worldly person having had the opportunity to see how history has come about. There is an inter-connectedness to everything and that becomes clearer with gaining an education. It's not for everybody, just those that wish to have the experience and growth that an education provides. Knowing is preferred over not knowing.