Yeah, I’m not buying that. It’s the story they tell you of course, but I think that’s a marketing lie.
Let’s be clear first that hardware is the platform. Your comment seems to agree with that. Note that for quite a long time, the Windows and Mac world used the same hardware (same CPU, same GPU), and therefore the same platform. They could have went together and specified a common API to work on both MacOS and Windows, and they could both expose all the hardware has to offer. Heck, if they really wanted to expose all the goodness hardware has to offer, they would give us the actual data sheets. They don’t, for various reasons that are generally tied to "IP".
They tell us sweet words about innovation, but let’s be honest they just want to lock us in.