I use it on iOS. So, for me the explanations really help. Because I understand the rules after seeing a few examples and the rules help me grasp it easier or see something subtle that I may have missed. Especially important in Russian.

But I can see it in a case where if you come from a language that has some grammatical overlap with Russian. It may not be as helpful, because she already has a mental language mapping for it. For English speakers or languages that some of these concepts are not native, it's quiet hard.

I do agree many native speakers do not know the rules. But they'e not the ones who would be creating the additional teaching modules. I'm sure there are plenty of Russian teachers who would love to make side money teaching Russian to non-native speakers and create explanation material.