Nice link.
I think it's academic at this point since new hardware will have to be HDMI 2.2 compliant.
But I welcome all upgrades in HDMI.
HDMI 2.1 fits my needs for the foreseeable future. I don't have nor plan to buy any 8K or > devices, although my AVR supports 8K, though not at the newly announced bitrate.
The ones lagging behind are the pc motherboard and graphics card makers, whose drivers often just suck and introduce dropouts. Handshake with AVR's, etc.
Not enough of an HDMI scholar to say why, just an everyday music listener who mainly uses a pc as playback device.
1's & 0's. Either they show up to destination device or not. Sometimes not.