Yeah, I suspect what you’re seeing is ultimately the user-facing impact of the developer issue that was mentioned here:
Plus the fact that it sounds like more of a “collection of useful components” than “a vision for applications, with components to help implement it”.
So if the default doesn’t innately work well for mobile, and there isn’t necessarily a unifying, prescriptive view on what principles folks should design toward, it does make sense that things would end up “functional, but feeling clunky”.