Heat can be reduced if you do it the OnePlus DASH method, let the phone tell the charger exactly what it needs in voltage and current so the phone's insides do no DC-DC conversion and so avoid the heat of conversion. If you can constantly fluctuate in micro steps the input then you will reduce heat and so maximize battery life.
I believe USB-PD does that. QC4 appears to be USB-PD with further optimizations. Hence if you standardize on USB-PD as the USB-C standard for power, a QC4 chipset is just a bit better optimized than non-Qualcomm, is I think the goal of Qualcomm.
I am just sick fed up with the glacial adoption of USB-PD, we can standardize on USB-C, one cable to be used for everything. Anker's fault here is shipping MicroUSB buds, and scarce USB-PD products. I'd like to travel with say just 3 USB-C cables of different lengths, a 3-socket USB-PD charger which can recharge 2 devices and a USB-PD powerbank with say a 60W total budget. Just go and build it Anker and quite faffing around.