I think it is more accurate to say that the knowledge of how OSes work, basic discrete math, etc. is important regardless of how that knowledge is gained.
A university education is only one way of achieving this knowledge. Even your last point of gaining knowledge about what you don't know about CS is achievable through other means (mentorship, online classes, study groups, etc.)
I think it is perfectly fair to suggest that a CS university education is a great way of achieving this knowledge, and it makes perfect sense to recommend that method if you followed that path yourself.
Personally, as someone who developed that knowledge outside the university system, I suspect that university is probably an excellent approach for most people, but I tend to encourage people to find the hunger for knowledge inside themselves and develop a passion for learning in whatever form it comes.