To be fair, the goal is the same.

1. Not everyone needs the sheer CPU, power, and costs of a 40 GB/s connection.
2. Higher wattage chargers cost more
3. 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)
4. Even if the CPU and GPU support a feature, the OEM can use a cheaper controller
5. 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.

While USB is now needlessly complicated and poorly labeled for consumer understanding, at least it succeeds in being backwards compatible so long as the physical connectors match (and all you need is a dumb adapter to convert any connector). If you have a 3.0 port on one device, a 2.0 port on the other device, and a 3.1 cable, you get 2.0 transfer speeds.

HDMI has the same kind of "issue". Whatever the specs on each component, throughput and features drop to the lowest common denominator when in use.

USB in 1996: lets let you plug any device into the back of your computer.

USB in 2024: phones, tablets laptops are going to charge at crazy voltages and we're going to show you 8k video all over the same port and you can insert it in both directions and we're still going to connect any device to any device.