Yes, as you said, they can help with learning grammar and vocab. The only problem I have with this is that they have too many such sentences. A few here and there would give some flavor to it but I think they could make memorable examples by mentioning the culture associated with the language. It’d be killing 2 birds with one stone.

Also, how often do we use the word “owl” or “bear” outside of Duolingo? 😂