> I think it should be consumers call as to what device they are using
If the sketchy charger bricks the phone but the customer is dishonest about using the sketchy charger at time of RMA, do you expect Google to engage in he-said-phone-said arguments with customers? "Ah but your big-brother device says it was plugged into a toaster oven last week."
So did Google? Not trying to be trite here, but that's essentially exactly the point. They didn't want to let a sketchy charger brick the phone, so they disallowed sketchy chargers.
You could say that the phone should try to accept any charge and never break, but that's a nontrivial amount of electrical-engineering and expense involved in accepting basically any wattage/voltage that a sketchy charger may produce.
Not to mention that the sketchy charger can brick the phone now. The phone can just regulate its own power supply and charge however it likes, all the charger does is supply current to the coil.
all of the battery charging control is in the battery, not the charger. The charger just generates the EM field (in this case) or a supply on traditional cables.
In a traditional wired charger, the transformer coils are in the charger. In case of wireless charging, one half of the coil is inside your phone. I am not an electrical engineer, but whatever current is induced there, you have to put it somewhere. So the argument makes some sense. Still not a nice move.
> whatever current is induced there, you have to put it somewhere.
No you don't. What is induced is an electromotive force, e.m.f., that is voltage. If the coil is open circuit then no current will flow. It's slightly more complicated than that because wireless charging uses tuned circuits not simple iron cored transformer but the general principal is the same and the control circuit in the phone can simply disconnect the coil completely in order to not accept any power.
A transformer is a two part system of two inductive coils. If you open the circuit on one end, the closed end won’t be able to induce a current into the second coil. It’s as simple as a single MOSFET controlled by some power management IC that measures current to prevent this from happening. It’s easier to prevent damage from wireless charging than it is from a physical connection.
If the sketchy charger bricks the phone but the customer is dishonest about using the sketchy charger at time of RMA, do you expect Google to engage in he-said-phone-said arguments with customers? "Ah but your big-brother device says it was plugged into a toaster oven last week."