If that was the case, the smartphone apps wouldn't have come about either. But they did, as evidenced by the made-for-smartphone apps that look silly on tablet

If that was the case, the smartphone apps wouldn't have come about either. But they did, as evidenced by the made-for-smartphone apps that look silly on tablets, which is what this whole conversation is about. The fragmentation in smartphones is incomparably worse than the tablet market. But Android has nice ways of dealing with it in display-independent ways, and they work.