I found videos on Youtube, exploring the differences between USB variations (Lightning or type 3 or type C, who can keep track of them all?)...
including what certain USB cables can deliver in the way of charging a phone, versus transferring data. A $10 charging cable may be unable to do everything a $130 cable does, and a Mythbusters episode tells more and why.
I understand there's a USB protocol called enumeration, which requires a peripheral to negotiate before it's allowed to draw high Amperage. Maximum available Amps has gone up with each revision of USB. It requires thicker wires to carry such beefy ratings. Can we be sure what rating and how many a dock can serve, and does it put up an alert saying "Ampere draw is too high"?