I'd still argue that there's a lot of value in some form of teaching (via book or video or whatever). If left to their own devices, novices will often come up with messy, non-idiomatic ways to do things.
Also, the answer to this question depends a lot on your previous experience with other languages. If you're well-versed in another C-like language, jumping right in and starting to make something will probably teach you a lot, really quickly. If you're more of a beginner in programming generally, you need a book or a teacher.
Not learning from books/teaching can make it hard to improve. I love reading other peoples code and thought processes because it often reveals how I'm missing something in my toolbox.
Studies have shown that one of the best ways to remember is to take a stab at a problem before learning the solution. So even quizzes on using libraries has helped me learn methods and concepts I would have not learned on my own if left to my own way of coding. I try a simple problem on my own before learning that there is a cleaner, more efficient solution. It's easier and more approachable to do that with small problems than trying to revise an entire document of code.
Lastly, I think a lot of experts underestimate the gap between novice and intermediate, where it's really hard and frustrating to attempt things that are a bit more complicated, requiring more background knowledge than just whats shown on the surface.
I sometimes get carried away and stop reading more after I cross some threshold which prevented me from noticing lot of nice things like best practices that were happening in the industry/or better design patterns etc..