They’re incredibly wasteful due to inefficient power transfer which is a huge issue with wireless charging.

And it’s not just wireless that’s inefficient; with a usb connection you’ll typically lose at least 15% in a good buck/boost stage and there’s 2 involved in a usb battery pack: one in the battery pack itself to step up/down from pack voltage to the negotiated PD voltage, and then another lossy stage in the phone stepping down to 3.7v.