The core problem is the large number of options.

When USB-C was announced and I saw the pin-outs, my immediate thought was, “This is going to be a support nightmare.” I should have written that down, so I could point at it as proof of my genius. :P But I didn’t know what a garbage fire USB-PD is.

I was thinking of Alternate Mode. Alternate Mode is what enables Thunderbolt 3 on USB-C. We already had an alternate mode for USB: MHL. Which divides HDMI ports between plain HDMI ports and HDMI ports that support MHL. The Alternate Mode multiplies the number of ways displays can connect to video sources via USB.

Not to mention what everybody else has commented on.

All these incompatible options are using the same connector. That’s obviously confusing to users and frustrating to support personnel.