Agreed, the part about immersion not being helpful was strange. He was immersed in English, both in school and probably in large parts of daily life. He simply turns on the TV to get English at home, all signage, newspapers, documents, are in English.

More importantly, being immersed provides an emotional reward for learning. If I learn these words, I can express these ideas and talk to people! This is different from just learning at school.

Edit: One thing I find odd about your post is the emphasis on confidence. It sounds like a correlation/causation fallacy.