It's not like immersive language classes aren't a thing. Even the normal foreign language classes at my university, past the third or fourth semester at least, only had 1 day of English while handling administravia, and then the entire class from then on was in the target language. During summer semester, all of the classes were taught this way, even the introductory ones.

Part of the difference between children learning something and adults learning something is that we have trouble achieving Beginner's Mind.

Finding techniques that work fine to be remedial or even insulting makes you get into your own way. In the extreme case, how do you fill a cup which is already full?

Less philosophically, each language you master gets its own language center in your brain, just as each finger you can control individually maps to an identifiable region of your motor cortex (and if you can't control your pinky, it's because they've blended together). Translating back and forth is a crutch for most, and a separate skill for others (eg, professionals). That's why when you ask your friend, "what did those guys say in the background?" you get something vague back. Nothing translates directly, idioms doubly or triply so.

What did that guy say? He said he's really mad at that other guy, (using a lot of colorful language), and I can say "he's mad" or we can go into why calling someone a dog/goat/cow/fish in this language is one step down from saying bad things about their mother.

> But... why?

I started it for two reasons. First there is close to no easy to read content when you begin learning Japanese and there is demand for such thing.

The second reason is to see how far I can go like this. It is a sort of thought experiment like you say in your comment.

I discovered after I started that Hans Ørberg something similar for Latin ( https://en.wikipedia.org/wiki/Hans_%C3%98rberg ). His Lingua Latina has been quite influential.

> Translation is not something to be avoided for the adult language learner. We should use every advantage at our disposal.

Because you're relying on the translator to accurately convey the meaning of words to you, which translators rarely do. Most professional translators and language instructors don't exactly have the best grasp of language themselves. They do some 1 to 1 translation of "monkey" and 猿 as if the connotation, denotation, and etymology are all the same when if you look it up, they're only kinda similar but not exactly.

English Wikipedia:

"Monkey is a common name that may refer to groups or species of mammals, in part, the simians of infraorder Simiiformes."

Japanese Wikipedia:

"日本語におけるサル（猿）とは、通俗的な意味ではサル目（霊長目）のうち、ヒト（古人類を含む）を除いたもののことである。"

Former talks about Simians whereas the latter apparently says (correct me if I'm wrong I don't know much japanese) colloquially all non-human primates. Is the translator going to know whether an orangutan or gorilla qualifies as 猿? Probably not, they're not even going to mention it.

Personally I believe people should learn a language well enough to read Wikipedia( or equivalent), and then continue only with media in the language in question from that point onwards.

> Spoiler: it takes children years and years of near-constant, directed input to acquire their native language to a high degree

You seem to be contrasting this with the implication that it doesn't take adults years of near consta