(Sorry to detour this thread for a sec, but...)
Because WiFi is the protocol that you use for transferring high-bandwidth, low latency data streams.
Bluetooth is low bandwidth and short range. It's a little radio meant to fit into tiny devices and transmit with just a sip of battery consumption. You
can stream some video over BT, but it's not at all ideal. (BT is still adding new audio codecs to try to fit good sound into its simple devices.)
For whatever reason, a dedicated wireless video protocol never fully caught on. (You shared a video of Miracast BTW, but that's actually WiFi, or rather WiDi.
Miracast was made by the WiFi alliance, and connects through the Wi-Fi Direct protocol. It is also unfortunately out of date, with no update since 2017 and lots of dropped supporters.) But even without a common standard, everybody went with WiFi, and for good reason. The ubiquity and wide capacity of WiFi allows way more options than just getting internet from your wall to your PC or phone or game box. WiFi routers and the receivers in for example Quest are made for the incredibly high data transfer needs of VR. (Wireless VR must be at a high framerate, high perceived resolution, and with imperceptible lag or drops. Some say that even the current and emerging new wireless protocols are still not enough for hi-res 90/120Hz needs of Quest 2/3 and beyond, and PS5 could have done wireless VR with its WiFi6 router but they still went corded with PSVR2. However, many people are happily leaving that USB cord behind, so the difference has narrowed if not been erased.)
VR today on a WiFi 6 device with an isolated 5Ghz signal (or better still, 6e with 6Ghz, if you have it close and direct enough) is pretty much the best and most acceptable wireless video option out there without a custom "wireless HDMI" radio/receiver (which I'm guessing are often extensions/hacks of WiFi radio protocols anyway.) That's why Quest uses it, and why it doesn't need a custom add-on "wireless VR" accessory to allow wireless VR tethering.