Isn't "calculus" a hard core counterexample?

I think parent speaks more about younger people. By the time you get to calculus, you're probably expected to be mature and somewhat independet.

You say "socialization" but I think the real word is "conformity".

Yes, societal institutions have a flywheel effect of normalization on those who pass through them. This is foundational to a cooperative society. They provide a background context to evaluate actions within, and define oneself in, or against.

Consider your Shannon Information. Meaning does not exist without context.

Socialization is an artifact, not the purpose, of most modern schooling in America; not like kids weren't socializing in mines and factories, though they likely had way more sense of consequence for their behavior in those environments. That said, education is also secondary except for, in urban public schools at least, the tier of students that are filtered for to benefit.

I think the socialization argument is a fallacy, in my experience there is absolutely no effort to guide or educate or provide any sort of understanding or framework of how to socialize, how to cope with interactions, your own feelings, etc.

It's just putting them all together and taking action if something too drastic happens, but there's no actual dedicated time for teaching how to socialize, you're on your own.