That fraction of a millisecond doesn't meaningfully translate into a better experience for users.

You're assuming the ISP has dimensioned their CGNAT properly and it's not congested.

Milliseconds matter for gaming, for example.

We are still talking a fraction of a millisecond, a few hundred microseconds at most. People are blowing out of proportion latency saved with v6, it's negligible at best, or at worst let's not forget IPv6 is two separate island because two tier-1 carriers refuse to peer (Cogent & HE).

Vast majority of people gaming are doing it via wifi