Earlier quoted context omitted.
I'm always a bit weary of theoretical stuff like this. The best way to learn a new language is to move there (preferably somewhere where people don't speak or don't want to speak your native language). I know people that didn't speak a lick of Spanish, moved to Spain, and in a year they're basically fluent. Of course, still struggling with stuff they might not be used to: gendered language, conjugations, and so on. B…
It's so strange to hear you and GP talking as if no one has ever learned a foreign language without moving to another country. The US military has been teaching translators for decades at the Defense Language Institute in California, and people learn languages to conversational fluency in university, albeit inefficiently. Duolingo is a game meant to be fun and collect subscription fees, not designed to teach any usef…
I speak three languages fluently (two prior to moving to said country; English, for example, is not my native tongue), so that's a weird assumption to make. With that said, I still think it's the most efficient way to learn a language, especially given how almost everyone's a nomad (especially in tech) these days.