It's not entirely uncommon that people feel they learn way better outside of school. I'd say that's a pretty huge indication of failure, given the fact that the entire purpose of school is learning.
In which case you'd expect (student-lead) learning outside of school would be superior, as you mentioned.
The "prussian model" strikes me as an urban legend.
i did fine in school, but until my upper-level college courses, i learned much more and more thoroughly from internet research and self-guided reading. i'm a millenial, so maybe things were different for older generations, but i also lived in what was considered a very good school district. i can hardly remember anything i learned in high school 10-15 years ago, but i can easily talk about the books i read at the time.
well, i can think of an exception -- i had an excellent english teacher that taught me how to write much better essays.