The chainsaw comparison is pretty lame, it is
especially designed to saw your finger off or anything else you're throwing into its jaws for that matter. So if you saw your finger off it did exactly what it was supposed to do. The shop can't control what you will use it for, if you accidentally saw your couch in half that's not their problem.
An overrated battery will precisely not do what it was bought and advertised for, the shop decides what batteries they have in store and what batteries they recommend to noob vapers. I don't see how that's even remotely comparable.
A better comparison would be: you need to move a piano over a 2nd floor balcony because it doesn't fit through the door.
You're going to buy a chain that can at least support 500kg, the hardware store sells you one that can "support 1 ton, easy" but when it instantly breaks, transforming the piano into a badly tuned pile of wood and metal, you realize you didn't get what you wanted to buy. Showing a professional at a different store the remains of the chain reveals it can barely support 200kg.
Will you go to the store and complain or think "oh well, in the end it was me who bought the chain, I should have researched chains and metal grades on the internet for a couple weeks before buying, so whatever".
Nobody is denying that in the end it's the consumer's responsibility to know about batteries.
The question is: should shops get away with being uninformed themselves?
Face it - the normal person going into a vape shop for the first time would assume they can trust what the staff tell them. They're the ones in the know about what they're selling, right?
Oh yeah, people should research it on the internet first, I forgot. Thankfully there's an official vape library everybody will instantly go to and only get correct information
I don't understand why vape shops being run by clueless clowns would be acceptable. It isn't and people should stop buying from shops that don't care enough to have a minimum knowledge about what they're selling and make it known to others when a shop is garbage.
I'm very much for personal responsibility but that's not limited exclusively to the consumer (why would it), that goes for the shop owner as well. If what they're selling, used as they instructed to, directly leads to an accident then absolutely they should pay the price.
The alternative is devices that are regulated so strictly that a monkey with a fez could sell them to you. That seems to be already in the making...