SLS requires Starship and the Lunar Gateway to get enough mass to the moon to make Artemis work. Starship can do the whole thing by itself. All things being equal, Artemis makes no sense.

But all things aren’t equal. SLS costs $4 billion per launch — just for the disposable rocket. SpaceX hopes to drive Starship costs down to $10 million per launch — or less — for a fully (and rapidly) reusable rocket.