We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
Two reasons: (1) Griggs vs. Duke Power made the use of IQ tests by employers illegal, so a proxy was needed, and (2) "the Government" decided to provide price support to colleges through the magic of spending other peoples' money.
Increase the demand and lower the cost, and this is what happens.
While certainly relevant, everyone is ignoring the biggest driver: the post WWII GI Bill that nearly doubled the enrollment of college students.
That huge increase meant several things, but the summary is that University Presidents started looking at degrees as though they were commodities.
The institutions had to grow their facilities to accommodate this huge influx, and then of course you were expected to keep using them after you built them, and anyway, who'd want to to see those numbers drop off? College education benefits the country! They needed to maintain or grow their "market" share.