Earlier quoted context omitted.
> Removable batteries create bulk, Not even remotely true. The LG V20 is very thin and still has a removable battery.
Batteries have to hold substantially more power now than they did 5 years ago. EDIT: Huh, I looked it up and I'm completely wrong. Battery sizes haven't changed.
Fast charging degrades the battery slightly faster than slow charging but it's not the end of the world in my opinion. I'm guessing it's much better to not keep your phone battery at a high state of charge for a long time, much of the chemical reactions that degrade the battery happens at high state of charge, than avoiding to fast charge it to 80%.