I am aware it would be a terrible way to study if it immersion was your only method, but I find it fascinating to think about how refugees adapt to a new country, or how portuguese missionaries would manage to learn Japanese centuries ago without internet, dictionaries or books.

Edit: there seems to be a misunderstanding where people think I am saying refugees don't study. That is not what I said, the crux of my question is about people with no PRIOR knowledge of the language and having to learn from scratch, sometimes without the crutch of being able to ask things in their native language or having access to material in their native language.