Should be detectable though, at least in many circumstances.

USB-PD has bidirectional communication, so at least in theory both ends could know how the cable is performing by comparing voltage and current measurements at either end.

If the cable drops too many Watts, the load can be disconnected.

Is this actually a standard, or would that have to be implemented like some sort of "extension"? And if so, wouldn't that break down the "universal" nature of the beast? As in a Dell laptop won't be able to communicate with an HP power brick (unless said extension becomes at-least de-facto standard)?

As I've commented elsewhere, I wonder if, at that point, there still is that much of a point in sticking with USB-C for what seem like fairly specific applications.

I mean, if we're at the point of carting around such a monster of a laptop, will an additional, dedicated, power-only connector make that much of a difference? Don't get me wrong, I'm actually somewhat tempted by such a thing, but just because it would be easy no move around, not for actually carrying on my back all day every day.

It's not part of the current standard[1] as far as I can see.

There are some mitigations though, like the cables must identify what they can handle (else the high current modes can't be used), and both ends needs to verify the plug and cable etc.

In theory though I don't see why they couldn't include this in the standard.

[1]: https://usb.org/document-library/usb-power-delivery

Now you will run into WiFi type problems where your cable gives you different charge speeds depending on the season and time of day. Service will degrade and you may not notice the problem and may never figure it out in the end.

Beats burning down the house though... Also in case of laptops, mobiles etc, the device can report the error.