If I were being cynical, I'd say their motivation is to get people to throw up their hands and say "I don't understand USB any more! Just give me the latest version of Thunderbolt. I know it supports the highest speeds and highest power, including displays and eGPUs, and all USB devices, and works on any new Mac."
It allows manufacturers (yes, many of the same ones on the USB-IF board) to "upgrade" their products by printing another label. USB-IF doing this repeatedly while being fully aware of the consequences can't have any other explanation.
This is just like the 4G-5G-5Ge debacle. Both being motivated solely by financial gain.
