For one, I thought charging slower was better, so could the increased heat be offset by that? Also, it's more heat per joule transferred, but over a longer period of time, is that not better than sudden heat from fast charging?
Heat is the primary factor, and even with fast charging the inefficiencies of wireless charging will mean the latter will dump more heat into your phone.
The constant current phase of fast charging does not generate much heat in comparison at given wattage as it's able to charge up your phone much more quickly at higher efficiency until it switches to trickle charging at ~80%.
Where did I say fast charging doesn't make batteries hot? I've built LiPo packs from scratch and rebalanced cells manually, I know something about LiPo degradation.
At any wattage, wireless charging at 70% efficiency will always generate more heat than fast charging at 95% efficiency.
If you want to compare 5w wireless charging to 100w fast charging, even then it's not obvious the wireless charging is better, because it will still thermal throttle and stay throttled for longer, at least a few hours. Meanwhile fast charging will charge it to 80% state of charge in half an hour and then trickle charge to full.
The notion that this is somehow "debunked" is just against physics.
Well I don’t know, if people tested and don’t see any difference, wouldn’t that count as “debunked”?
A quick internet research shows the Internet consensus is, wireless charging does not degrade batteries faster. At least it seems there is no empirical data proving otherwise, which at the very least would indicate the difference is small, if any.
I think until I see (good) empirical data proving either of the theories I’m going to stay skeptical.
I wish people would stop using this phrase.
Especially when they couldn't be more wrong.
Heat degrades batteries, wireless charging generally comes with more heat from the lower efficiency.
But at the end of the day it most likely won't matter as people get new phones every few years anyways.