Yeah, it's just that it took time to implement, especially since IPv4 ossification (at the time when it was explicitly in works to be removed!) happened partial

Yeah, it's just that it took time to implement, especially since IPv4 ossification (at the time when it was explicitly in works to be removed!) happened partially through introduction of hardware-assisted switching. But we have had fast path switching for IPv6 for I think 20 years now, and it's generally available. Hell, some big networks, the kind where having fast path switching, moved fully over to v6 and simply do not transit v4 (Deutsche Telekom, for example, whose skeleton network is now "flat" IPv6 network and any v4 traffic is encapsulated to 464xlated