Remember when people were mad about Apple patenting rounded corners? This would be as bad.
Consider the situation with standard NEMA 5-15R receptacles. As far as I'm aware, the design is not legally protected, but any manufacturer who made a '5-15R' receptacle that couldn't carry 15A--or any device manufacturer who decided to re-purpose the pins such that the ground conductor carried 240V--would have legal problems if they brought their product to market.
This is where USB-PD should be: in a situation where physical connector compatibility brings with it enough design assurances that any pairing of legally-available devices won't blow up, catch fire, or burn out. Ideally, any USB-PD device pairing should work, but at the moment the bare minimum needs to be that any device pairing is safe.
Someone making a port the exact size and shape of a USB-C port (within tolerances) is doing it for the purpose of being compatible, and telling them to meet the (non-onerous) spec to be allowed would not get nasty headlines.
People put TRS (3.5mm audio) jacks on random proprietary wall-chargers. They don't do it so that the charger can "be compatible with" the analog-audio ecosystem (what do you want to do; plug your charger into an amplifier?)
No, these manufacturers use TRS jacks, because TRS jacks (and sockets) are cheap parts. (Remember, they're not making these parts; they're just ordering them, in bulk, from some supplier that has a warehouse full of them. And that supplier doesn't care what they're used for; they just want to get them sold.)
USB-C connectors are now also seemingly beginning to be cheap parts.
But even if they want to, it would be better if someone stops them.