Re: I don’t see how USB-C solves the charger-zoo problem......
Indeed. I'm sure mileage varies, but for all my USB-charging devices1 I've always just had a couple of those kits that have a cable and a set of adapters for various USB sizes, and the assortment of USB chargers I've accumulated over the years. Phones, tablet, Kindle, that old MP3 player I sometimes dig out for when I'm working on the house - they all charge just fine with whatever cable and charger I use.
I keep a couple of chargers in my computer bag and have various ones scattered around the houses. (The latter stay plugged in; they dissipate negligible heat, which means they're using negligible power.) I've never had any reason to look to see what they're rated for.
1Refusing to use Apple products has solved the Lightning problem nicely.