The thing is that their whole marketing and selling point is mostly to people who don't have real strong motivation or focus to learn a language or don't have the time. E.g. to the tone of "you'll need to do this for just two minutes a day", "it'll feel more like a game", " much easier than in a traditional classroom setting ", etc. But the truth is that it doesn't really work that way; someone with focus and motivation learning grammatical rules and more in a classroom will always be either more effective or progressing at least at the same pace (or at least be just as ineffective). Their business is more about selling the idea of learning a language and that it is actually easy, partly by presenting it in a gamified way. It kind of works because people fall for it and buy a subscription for ~3 months but probably eventually stop. They then need new subscribers and have to double down on that marketing/selling of the idea.

In reality, there is no shortcut to learning something. It's just about having the curiosity, motivation and discipline to do so. And many people may think they have that or are enticed by the idea of learning a new language but their life doesn't depend on it enough to have the aforementioned qualities to do it.