Because it will take forever and a day to charge. Actually, even if it's a legit charger that properly fast charges according to USB rules, it may not work.
SuperCharge beat out Google and Apple's simpler systems as well as other adapter-based systems like OnePlus's Dash Charge and Motorola's Turbo Charge.
The median top rate for this phablet, as measured by one researcher, is 10.5 watts. And it's even worse if you leave the screen on.
A new cable, perhaps an extra dongle, a new power adapter and somewhat faster charging may await if you purchase an iPhone 8 from this fall.
Qualcomm Quick Charge 3.0, Dash Charge, Super VOOC and all those other standards might have to be abandoned. Or Android Nougat, who knows?