This proves the OP's point. Duolingo is trash if you aspire to fluency. It's only useful in fluency as an additive to a robust training program. You don't get fluent by following Duolingo alone.
I disagree. Duolingo is not trash as the op suggests, it's a great fire starter and makes you able to use other materials by handling the intro well. Peppa Pig is a sustainable language learning tool if you did something before to learn the basics and Duolingo handles that part well for free. How is that trash?