No, this is 5V/3A and 5V/1.5A as communicated via PD 3.0. In this case you can achieve the same result without PD (well, almost - you still need it for role swap), but that's not what I was talking about.
What scenario would your laptop be providing power (being the source), while simultaneously being the receiver of data (data sink)? Not sure I see the use case for that, regardless of whether you can achieve 5V/3A over PD.
You need PD for power role swap. You also need PD for alt-mode negotiation. You can get a 5V/3A contract to power a USB-C hub with DisplayPort, for example - that won't work with simply signaling 3A with a resistor.
Understood you need PD for alt modes, that's a given. I never thought about the scenario where you have a powered USB hub and you switch from powering it via a brick to powering it via your laptop... interesting, and actually very reasonable scenario. I guess given you have PD already built-in, it's not too hard to integrate that functionality either.
Many PD controllers support this for 'sourcing' (5V/1.5A or 5V/3A) natively, since it's a common use case for laptops.