> It was suggested that a website operator deploying IPv6 would somehow improve the end user experience by virtue of avoiding CGNAT and I was questioning that.
Non-legacy, newly formed ISPs have to spend a lot of money on either buying or leasing IPv4 address space, and even then if they grow they probably won't be able to keep up, and so have to deploy 100.64.0.0/10 to the WAN interface of CPEs and then buy a bunch of CG-NAT hardware.
The problems are on not entirely visible at the end-user side of things because of the Herculean efforts by ISPs.
IPv4-only services are thus externalizing the costs of connectivity to ISPs (especially newly formed ones).
> externalizing the costs of connectivity to ISPs
Isn't that literally their raison d'être? Point taken that in aggregate it increases the costs of network operators but still that's got nothing to do with an individual instance of an individual user visiting an individual website.