TBH, I don't even personally like Duolingo-style programs for getting down the base vocabulary, because, while it's a generally more pleasant experience than other options, I find the approach to be relatively slow and inefficient.
Here's a video (in French) that I found reflects my own experience quite well: https://www.youtube.com/watch?v=-KQ1qRJ2wQc
In a nutshell, I've got two complaints. First, while flashcarding is wicked efficient (I'd say essential) for review, it's not a particularly good tool for learning things in the first place. And an overly flashcard-oriented approach has real problems with a sort of streetlight effect: You tend to get stuck on what's easiest to illustrate with pictures, which often isn't what's most useful for communicating with others.
edit: Also, for what it's worth, the existing research seems to indicate that, while subtitles in our target language can be hugely beneficial, subtitles in a language you already speak actually inhibit language acquisition: https://journals.plos.org/plosone/article?id=10.1371/journal...
(There was another study with Brazilian English language learners that I found more compelling, but I'm unable to find it right now.)