Notably, you need the $60 “full” version to get the ATX power control breakout that attaches to the perverse physically-USB-C connector that has the ATX signals (why? why did they make this abomination?..). Or make your own, I guess, that’s always an option (if only USB-C connectors weren’t absolute ass to solder).
Probably because USBC connectors are really cheap. If this was 5 years ago, they probably would be doing something terrible with a usb 3 A connector instead.