Well put! I think you covered a lot of the points I was thinking. I think if you are active in your language learning journey, you can use Duolingo as a tool to get to your goals, but that's the thing - you have to be active and in the driver's seat of your learning. I usually use Duolingo to understand the sounds of a language, and then after that, I'm off to other tools. It does suck that they only have bigger languages on there - like when I tried to learn Farsi, that wasn't there.