I mean yeah, there's extra stuff layered on top of the underlying protocols that is badly designed. Docker was built with a hard dependency on IPv4, so was the Dat protocol. If these things were designed properly from the start we wouldn't be having these issues.

Apple was smart here, they mandate that iOS apps must support single stack IPv6 only and perform functional testing of that as part of the app store process. Devs can't get away with pretending it's not necessary and not wiring up support for it.