Yes. USB-C Video Port not working with MacBook or other laptops - #21 by Philips_Support_P
DP alt-mode would have required yet another chip or two in the PPM, driving cost up. That’s my guess.
Edit: The only video alt-mode supported by the PPM USB-C video port is alt-mode DP, not HDMI → Connecting laptop using USB-C cable - #21 by Philips_Support_P