First of all, you’re implying it runs latest Windows - but Windows 11 shipped a few years ago.

Second - not really a fair comparison. 18 years ago the iPhone didn’t even exist. And the oldest model (17 years old) had really weak hardware. 4GB of storage, 128MB of RAM, and the CPU was an order of magnitude slower than current spec CPUs (it was also 32 bit - and 64 bit ARM is a completely new architecture - similar to the failed Itanium).

Even if it was supported, it would be a horrible experience.

it’s just never used or enabled in the software by default

…and most people who own those devices have never heard of IPv6 and don’t know how to enable it. They just won’t be able to access your website. If Amazon dropped support for IPv4, there wouldn’t be anything i’d be able to do to deal with the fall out. I’m not going to send a technician to every single home of every customer I have. What I could (and would) do is move all my stuff off Amazon.