The HDMI Forum, responsible for the HDMI specification, continues to stonewall open source. Valve’s Steam Machine theoretically supports HDMI 2.1, but the mini-PC is software-limited to HDMI 2.0. As a result, more than 60 frames per second at 4K resolution are only possible with limitations.
Because that would open source certain implementations they want to hold captive.
It also enforces closed source drivers which can be shipped with spyware/crapware, further extending profits for companies… companies that happen to make up the HDMI Forum.