"If liberal arts education was on equal footing as STEM, there wouldn't be the jokes"
'Liberal arts education' has become a code word for drinking to excess five nights a week and cheap casual sex with classes you can just show up to occasionally and pass. Actual literal liberal arts education is available in very few places but might be just as valuable as STEM for those who really get it.
"MIT/Stanford's primary value (to investors) is to act as an unspoken IQ test"
That is in very little dispute. To investors and employers, elite university admission is an IQ test and graduation is a test of social class values -- it's a test of whether your family is stable and wealthy enough to support you financially, emotionally, and socially through four years and not interrupt you by needing you to support them financially, medically, or as free child care. Smart people from stable upper middle class families are valuable employees while the practical stuff you'd learn at MIT, especially in CS, is very easy to pick up on the job.
"Supreme Court justice, you have to go to Yale/Harvard Law -- and you must finish those degrees. If you want to be a neurosurgeon, you must finish medical school."
Note that those are non-market jobs. You can't pick your own Supreme Court; you have to deal with the one politics subjects everyone to. You can't pick your own neurosurgeon just because he's good; you have to take one of the ones the state licensing board, state courts, and insurance companies choose for you. And people with political power like to support the process of educational hoop jumping for various reasons -- some of them good.
Customers, entrepreneurs, and investors risking and spending their own money are more interested in results than pedigree. That's why the lightly regulated software industry sees so many dropouts succeed. Dropouts do well in construction trades, agriculture, and other less bureaucratic credential dependent industries, also.
Industries like Wall Street, where the primary source of income is scamming politicians, pension fund managers, regulators, and the public, depend even more heavily on pretty credentials than regulated industries like law and health care. Ivy league degrees are really valued on Wall Street because perception is so much more important than results.