[bert64]

They are fully compliant, SLAAC is part of the standard whereas DHCPv6 is an optional extra.

DHCPv6 also does not work without RA. DHCPv6 just assigns an address, a routable prefix, dns servers etc, it does not assign a subnet or any routes, you need route advertisements for that.

[ale42]

Seen like this, you can also argue that DHCP is an optional extra for IPv4, but it almost essential in most networks. Sure, IPv4 has no SLAAC that can be a valid alternative, but still, given that SLAAC doesn't solve every use case...