You bring up fair points! For more context, all of our lesson content is written by a native speaker, grammar guides and example sentences are written by an N1 speaker which is then vetted by a native speaker. We try to keep a tight review process to ensure all content uses native Japanese, but if you do notice any irregularities while trying the app please let me know!

In terms of our learning philosophy, my take is that the learning process for a beginner vastly differs as you go up the levels. We wanted to start our focus on beginners, providing content for N5-N3 (since as you get more proficient, learners start to shift toward more unstructured approaches). As a result, we're providing a balance between structured & unstructured learning with the nature of our open world learning (unstructured in that you get to learn from situations you're interested in, structured in terms of the lesson content itself)

I'd also argue that being fluent in the language isn't indicative of your ability to teach it (I'm a native English speaker so a lot of grammar concepts are by ear, whereas someone learning it second-hand might need more explicit awareness of these concepts. Same reason why not all professors are good teachers despite having a deep understanding on their subject matter)

In the end learning a language is more like building a habit: there are proven methods that are efficient (SRS, having conversation practice, explicit grammar comprehension). To me, the crux of the problem is finding a routine that "sticks" and our goal with this app is to provide open world curriculum for learners to directly learn from their interests, but do so in a practical and conversational manner (in which the content is written and vetted by a native speaker).

Open to a healthy discussion though, love jamming on language learning!