Learning primarily through listening and talking only works if you have an enormous amount of high quality data, ie, the situation you're in as a baby when you're surrounded by native speakers who are producing speech for hours every day.

If you are an adult and want to spend, say, a couple of hours each week learning a language from scratch, especially without constant access to a native speaker, your initial progress will be much faster if you study grammar and vocabulary in a traditional class from a text book, than if you just try to pick up patterns from listening to the TV or something.

I can't source my claim. I attended a public lecture years ago from a researcher about exactly this misconception.

> Natural language acquisition is almost entirely listening and talking.

And it's bootstrapped by 1+ year of listening before being even able to speak, let alone talk intelligibly. That's not really an appealing process to anyone beyond that age.

Your comment sparked an idea of a conversation with an agent where at any time you could ask, “what’s this word?” and it would respond with an image explaining it. I’m surprised there don't seem to be voice apps that integrate any visual content.

> Natural language acquisition is almost entirely listening and talking

Listening and reading. Talking goes last. See Steve Kaufmann, for example

> The reason traditional material doesn't attempt immersive techniques is because it is much much easier to print a static book than it is to produce interactive and adaptive content.

No, that's not correct.

First off, you can provide immersion with static books. A common favorite here on HN is Lingua Latina per se illustrata ["the Latin tongue explained by itself"].

Second off, there are two reasons that traditional material doesn't do this. The biggest one is student demand; people are afraid of immersion. The second is that the traditional approach is faster. It's lower quality, and it tops out well below the level you hope to reach, but it's faster, not slower. It takes babies a year to learn to say they're hungry. It takes an elementary school class studying a foreign language less than a day.