While I agree that people need to make mistakes (giving newbies room TO make those mistakes is an important part of mentorship imo), I couldn't disagree more with the idea that there's nothing to learn about architecture from a book.

A vast majority of the mistakes people make are avoidable ones stemming from ignorance. They're often missing the "why" part of architecture. "What does it mean for an architectural choice to be 'good'?" This can 100% be "book learned" and then mastered through the messy process of experience. You have to at least know the rules to play the game. Many people skip the "know" part.