I wouldn't feel good about anything that's not focused on a single language.

You end up with the Duolingo problem where you know to say the names of 20 different fruits but not how to introduce yourself.

> You end up with the Duolingo problem where you know to say the names of 20 different fruits but not how to introduce yourself.

Not sure if this is a duolingo problem. There are of modules in duolingo specifically for saying your name. I think its the travel module.

(Duolingo problem(, AIUI): Duolingo is designed around such premise that, by exposing your subconsciousness to such small set of words and phrases in target languages, your brain should be able to trivially construct output shims from Universal Grammar, which must exist, to desired languages; but that doesn't work in practice and you end up with small set of words and phrases your subconsciousness had recorded)

Never seen that in Duolingo. It starts with the basics and phrases, not random useless vocabulary.

I was going to Italy and started using Duolingo to try and help. I learned such useful phrases as "the children have bread".

Duo has a different problem for me. The lack of focus means some languages don't get features. Chinese still doesn't have Stories (there's an unofficial version of it, but we've been waiting years).

the Duolingo's problem it is not because they have a bunch of languages, it is because achieving fluency in a target language it is about been able to produce/generate phrases, and they just move you to consume and sort words and phrases. in the case of any AI Language tutor, the student must produce phrases in order to practice, and that makes them advance in the path to achieving fluency