They can.
USB-C goes up to 240 W now and the law has been amended to acknowledge the new USB PD spec. Devices are also allowed to have proprietary charging ports but must include a USB-C port capable of showing the full power draw of the device (or 240 W of they need more than that).
So a big gaming laptop might have a USB PD-capable port that supports 240 W and a barrel jack that supports 350 W.