> Why don't you want every device to have a public IP?
Suddenly, your smart lightbulb is accessible by everyone. Not a great idea.
> With IPv6, if you want a peer-to-peer connection between firewalled peers, you do a quick UDP hole punch and you're done - since everything has a unique IP, you don't even need to worry about remapping port numbers.
There is no guarantee with IPv6 that hole punching works. It _usually_ does like with IPv4.
Suddenly, your smart lightbulb is accessible by everyone. Not a great idea.
> With IPv6, if you want a peer-to-peer connection between firewalled peers, you do a quick UDP hole punch and you're done - since everything has a unique IP, you don't even need to worry about remapping port numbers.
There is no guarantee with IPv6 that hole punching works. It _usually_ does like with IPv4.