Question about LC-Power LC-M16-4K-UHD-P-OLED

The manual says the following:
"Note:
The touch screen of the monitor is only available when the input source is connected via USB-C; with an
HDMI input source, you need a USB-A to USB-C cable (not included) to use the touch function.
included)."
The second sentence doesn't make much sense to me. If the PC is connected via USB (but in my case C to C), then there is no need for an HDMI cable at all.

Yes, but you also have to connect a USB cable to the PC to activate the touch function.