But if you don't know the underlying platform, how can you be sure that your framework is high level enough or that it can do everything that's possible on the platform? You either have a framework with escape hatches (that'll require you to drop down to the bad stuff) or you have to wait until the framework catches up to the platform. Actually now that I think about it, React would fall in both camps.
How else can you fully grasp what's possible on that platform and the costs of different abstractions?