That leaves out all the "what is a computer?" devices that had all sort of plugs that wouldn't be barrel: tablets, chromebooks, raspberry pi, e-readers etc.
Same for all the smaller dedicated devices (audio recorders, camera, controllers etc.)
Those didn't go the barrel plug route in the first place to allow for charging through the same port, and would have been a loophole if barrel was mandated. USB-C was honestly the only option that made sense IMHO.
Most of those used either USB or a barrel plug depending on their size.
raspberry pi, e-readers
USB.
Same for all the smaller dedicated devices (audio recorders, camera, controllers etc.)
Many of those use smaller barrel plugs, appropriate for their lower voltage.
The main problem with USB-C is the tiny fragile connector (search for images of "bent USB-C"), and the fact that it's a standard that tries to be what should really be a bunch of separate standards. It's hard to get a barrel plug wrong. It's too easy to get USB-C wrong, and cause damaged devices:
Same for all the smaller dedicated devices (audio recorders, camera, controllers etc.)
Those didn't go the barrel plug route in the first place to allow for charging through the same port, and would have been a loophole if barrel was mandated. USB-C was honestly the only option that made sense IMHO.