And the higher level libraries mostly do it for you, too, even if you directly specify IPv4 addresses in your code (due to NAT64 [1]). I think it only even requires special work from you as a developer if you're using low-level or non-standard libraries.

[1] https://en.wikipedia.org/wiki/NAT64

The problematic low-level libraries are standard, and effectively impossible to fully deprecate since they're decades old and part of the socket API.

I think currently Apple still helps you with these via "bump in the stack" (i.e. they can translate internal v4 structures and addresses into NAT64-prefixed v6 at the kernel level), but they probably don't want to commit to doing that forever.