Awesome writeup! Another thing that I should probably have mentioned earlier is that the resistors are across D+ and D-, allowing the device to know that it's

Awesome writeup! Another thing that I should probably have mentioned earlier is that the resistors are across D+ and D-, allowing the device to know that it's A) not plugged into anything it should be talking to and B) what the output of the charger is. This get's really entertaining when you start talking about USB C where if the resistor is used incorrectly, you can start doing real damage to device and charger.