I speak 3 languages fluently and always wondered if anyone really managed to learn anything via Duolingo? It seems similar to learning code syntax and understa

I speak 3 languages fluently and always wondered if anyone really managed to learn anything via Duolingo? It seems similar to learning code syntax and understanding but in practice not being able to communicate. To me it doesn't seem like any of these mechanics would help to actually learn, just to increase retention and revenue. I wish there were still companies who's NorthStar would be customer success and in this case proficiency instead of making people stuck to their screen longer. But I get it... investors.