Just like building a skyscraper doesn't require a degree. You don't need a degree to lay bricks, pour cement or assemble rebar. But you do if you're the one designing the structure in the first place.
There is a lot of knowledge to be gained by experience, but sometimes it's useful to have knowledge gained from books, and in particular from books you had no interest reading in the first place (which is the real value of a degree: forcing you to go through a process that includes stuff you like and stuff you dislike).
But goals for students with paths including a variety of subjects both obviously useful and apparently useless seems to be (in practice).
I occasionally come across situations where those useless subjects suddenly contribute something useful for the problem at hand. I would never have studied them by myself unless forced by the goal of finishing college. At the very least, I would have never studied them to any sufficient depth to make them useful.
It's really not obvious when you're studying. I often use knowledge that seemed useless at my time at university, but it has surprisingly come in handy every now and then.
It's not about being dumb. You're taking it personal when no offence is meant. Understanding the difference cache hierarchies, or how you reach consensus in a system without a central authority, or to what degree various normal forms of data affect you, or being able to design a sound and complete DSL, or a lot of other things. That is what you get from a proper CS degree.
Does that mean that you cannot program of design programs? No, but there are people out there with more education better suited to design, say, a large scale medical system where certain guarantees must be given.
There is a lot of knowledge to be gained by experience, but sometimes it's useful to have knowledge gained from books, and in particular from books you had no interest reading in the first place (which is the real value of a degree: forcing you to go through a process that includes stuff you like and stuff you dislike).