As a language teacher who loves Duolingo, I would like to make a general comment about the so-called ‘meaningless’ examples that seem to give us learners so much trouble. I do get that they are there to teach us Spanish (in my case) and may have a grammatical or phonetic purpose, but I find that my mind usually tweaks them to make logical sense. For example, when faced recently with: Yo había muerto, I automatically translated with: I had NOT died, and cried another heart. No big deal, but it reminded me of a study conducted by psychologists and educators in Harlem a few decades ago. The myth was out there that the children of Harlem were slower at learning to read than children in other city schools. Until they gave Harlem children readers that were written in their vernacular and reflected a more familiar reality. Then these children’s reading abilities shot up. So, I would urge the Duolingo team to steer us away from dogs drinking red wine or crabs drinking milk, or even kings counting strawberries for the luncheon of colonels… Still keep us the good work Duolingo!
As far as I've seen from my studies here, the "the dog is drinking wine" type sentences tend to come up very early in the tree, when you have a vocabulary of maybe a couple of dozen words. It's hard to produce a wide range of sentences, exercise all the required grammatical points, and reflect "familiar reality" with such slender resources. I find that the later lessons tend to be more realistic (and, alas, less entertaining), albeit with the occasional oddball sentence thrown in to keep you awake.