Using the iMessage analogy, we're currently in a state where green bubbles can't interact with blue bubbles at all. Nobody should be expecting full interop with a corporate platform, but for the long run I'd rather have partial interop at arms length.
Embrace extend extinguish only applies if platform is so focused that it cannot sustain itself without the extend phase, and the extend phase cannot happen without something to embrace.
The official VR apps for Skyrim and Fallout 4 were lacking out of the box, but they're damn good experiences with mods.