Cross-platform development is not like the other problems (too many poor quality frameworks, unsolved problems like scaling, etc.) The main problem with cross-platform development is that the creator of the platform usually has no incentive to work with other platforms; quite the opposite. That road leads to commoditization. Users and developers want commoditization, but sellers do not.

Another problem is that often if you create a platform, it is because you want to do something different than established platforms. This inevitably makes cross-platform difficult.