> Back around the late 90s ISPs wanted to have everyone pay per device on their local networks. NAT was part of what saved us from that.

But with IPv6 a single device may have multiple addresses, some of which it just changes randomly. So this idea that they'll then know how many devices you have and be able to pay per device isn't really feasible in IPv6.

A single /64 being assigned to your home gives you over 18 quintillion addresses to choose from.

If the ISP really wanted to limit devices they'd rely on only allowing their routers and looking at MAC addresses, but even then one can just put whatever to route through that and boom it's a single device on the ISP's lan.