To be fair, the goal is the same.
- Not everyone needs the sheer CPU, power, and costs of a 40 GB/s connection.
- Higher wattage chargers cost more
- Not everyone needs a USB port that does video out (even if it should be standard now that virtually every new GPU should be compatible)
- Even if the CPU and GPU support a feature, the OEM can use a cheaper controller
- The controller firmware can lack support for a feature or be buggy
The USB forum can only solve points 4 and 5 without raising costs on the cheapest hardware.
Wasn’t USB4 based on Thunderbolt 3?