It was at the start of the IPv6, but then disabled because companies were afraid of IPv6 compatibility with IPv4, which may be used to penetrate firewalls.
Huh, I had no idea, but I can see that happening. The bigger "nope" that comes to mind is wanting to replace NAT with every device having a public IPv6. Yes a firewall is theoretically superior to NAT, but it matters in practice how stupidly secure NAT is by default.