No wonder why Apple took DisplayPort-Mini port for their Thunderbolt interface. Back in 2011!
To use Linux at 4k at a high refresh rate with a TV or other screen that only has HDMI ports, they sell high-performance DisplayPort to HDMI adapter cords for like $30 on Amazon. My Bazzite machine works just fine on a 4K tv at 120hz, and even enables HDR now which it didn’t before with the regular HDMI cord.
If the HDMI forum thing doesn’t work out, I totally could see Valve offering a DP to HDMI cable just so folks don’t need to do extra searching to get the best performance out of their new hardware.