VR is in kind of a weird spot. Because it's treated as a console/peripheral/basically a screen, depending on where you are.
No, people understand generally that Xbox and PS are different ecosystems. But it's not like we need different ecosystems for our Televisions.
Mobile phones are in a weird spot, where they are separate ecosystems; but most things are so generalized that it barely even matters.
There are console peripherals that do work on PC, mostly the DualShock 4, Dualsense, and Xbox controllers.
I don't think it's surprising that people want more utility from expensive peripherals. Imagine if we had to buy PlayStation TV's and Xbox TV's in order for our consoles to work. (Not the best comparison, but it's not a crazy one either).
It's only 'recently' since you can easily use PC monitors on consoles and TVs for PC. Sure TVs were never tied to particular consoles (apart from some add-on experiments like PS1 LCD screen) Yet with VRR you still run into compatibility issues. Btw we do have different eco systems for our tvs nowadays, Roku, WebOS, Google, TizenOS, FireTV :/ Might not matter that much, might start to matter a lot for game streaming.
VR will get there, there just isn't an HDMI standard for VR yet. Tracking systems are still evolving as well as the controls and display technology itself. It's a lot more than just a display. And because VR is so sensitive to input delay and steady frame rates, it's not that easy to just swap one out for the other.