The registration is not yet automatic. It becomes automatic in December 2026.
Until then, males are still required to register. The automatic registration is somewhat of a no-brainer, as the government has, since it was reinstituted in the 1980-'s, routinely contacted 17 year olds telling them about registration, and then frequently reminding them to register. They know, and have always known, where each person is, so the registration process was somewhat superfluous.
Also, the selective service is not just for a military draft. It is also authorized for use for other government programs that are not specifically military, but could be used in case of some other emergency, such as a pandemic.