If you click "Domain join instead" on the Azure AD login screen it gives up and asks you to make a local account, which you can then use to join the domain once

If you click "Domain join instead" on the Azure AD login screen it gives up and asks you to make a local account, which you can then use to join the domain once you get to the desktop. Domain joining from setup is impossible (it requires a reboot, and then group policy could push something that breaks the rest of the out-of-box experience), so it's safe to assume that will always be there (unless they do a major change to how AD joining works, but they probably won't since they consider it "legacy").