Not hating, I don't know from which year this is from, didn't even know it's a development kit, and although the capabilities I mentioned are recent (and by recent, thunderbolt 4 has been around for at least a couple years, PD 120w for around the same or even more), a single usb-C has been capable of driving a portable device, that needs charging and a display output, from at least 7+ years.

You can call me cynical, but yes, if I see a strange double usb-C port I think it doesn't really make a ton of sense and the first thing I think about is a strange trick to transform a standard technology in something proprietary, especially since nintendo has done the same with the switch 2 by implementing non-standard usb c in their dock.

This is not a recent revision. TB4 is from 2020. USB4 is 2019.

The real answer to this question is that Thunderbolt is an Intel standard and adds significant licensing and IP overhead to unit costs.