Generally speaking, it's not that it's impossible someone who doesn't go to school will learn things, it is just less likely.

I generally expect a greater degree of people who went to school (therefore COULD benefit from instruction) have a higher chance of foundational knowledge helpful in a computer based career.

At the same time, I met dozens of nitwits while at school who can't code their way out of a paper bag and misunderstood half their classes.

School increases their likelihood of being good, it doesn't guarantee it.