I don't think the issues normally present when just charging--I'd say charging is the simplest task. But when I tried to plug a USB C monitor into my mabook the other day I went through every C cable in the house to no avail, despite the fact they all do USB C PD just fine.
For Alternate Mode to work, only cables with high-speed lanes will work (aka USB 3.0 cables). Power Delivery doesn't need these high-speed lanes at all.
I figured it was something like that :) but that does nicely illustrate the problem of C: despite the fact that the ports are all the same, there's reliable way to know if a cable will work for the purpose I'm going to use it for.
Sure, basically any cable can _charge_ a device at some speed, which is absolutely my common application, but for shoveling bits around it's much more complicated.
