The thing that sorta gets me about Duolingo: If it became mainstream for everyone to do what is essentially 5 minutes of anki every day (which is kinda the Duolingo pitch), language learning would be kind of a bad candidate. If you spend 2 years memorizing 400 words you still aren't close to knowing a language.
But there are many situations where memorizing 400 distinct things is pretty useful: countries, capitals, recipes, history etc.
It's worse than anki because there is no SSR built in ( at least when i was doing it ).
>But there are many situations where memorizing 400 distinct things is pretty useful: countries, capitals, recipes, history etc.
Just memorizing 400 vocabs alone is actually pretty good early on because then you aren't tied to practicing grammar with childish content like " I went to school by bus yesterday" because of limited vocabulary.
I spent the first year alone learning about 2000 vocab without any grammar. And when I go on and do grammar I can actually practice with interesting content that related to my daily life. I now recommend new learner to learn their vocab by N + 1 level relative to their grammar.