Good FOSS software and reliable service providers? Etc.
Yes, it’s not the same, but it can be used to bridge private addresses onto a public network, which is basically what NAT is trying to achieve. If you’re running an ISP and don’t want customers to be directly accessible from the internet, it seems reasonable. In an ISP setup, you would issue private net addresses and just not do the translation if the customer doesn’t pay.
Yes, you can achieve the same thing another way, but I could see them deciding to issue private net addresses so customers don’t expect public routing without paying, whereas issuing regular public IPv6 addresses makes it clear that the block is entirely artificial.
