v6 mostly is just v4 with more bits, and it has a reasonable migration path from v4 too. I don't think a more reasonable migration path is even possible given the constraints of v4.

About the only thing new in v6 that's not already in v4 is SLAAC, which isn't very complicated. Routing works the same, the addresses work the same, DNS, TCP, firewalling etc all work the same. If anything they removed complexity by dropping broadcast and making NAT unnecessary.

People just have some very weird misconceptions about v6, and will frequently argue that e.g. it was badly designed for not doing a thing that it does actually do, or for not doing something impossible.

The biggest thing is all the v4 addresses are no longer valid in v6. They had a choice and went with making a separate parallel network with new routes. This means DNS DHCP etc work similarly but are completely different, and the separation between DNS v4 and v6 of course is never clear in any router UI, network config file, etc. And the routes themselves are different.

SLAAC itself isn't complicated, but it means introducing multiple kinds of addresses, which is complicated. Privacy addresses were the latest thing. The history of this has left the defaults in a wacky state, like I got a new router and idk what to expect if I enable v6 on it. Even disabled v6 on my laptop cause idk what it'll do when I join someone else's network. Default should've just been DHCP+NAT from the start, not a loaded gun aimed at foot.

And SLAAC means random addresses that are human-unreadable. "Just use DNS" but nah, nobody will do that.