People don't need to take off from Earth on the Starship to get to the moon with it. Dragon 2 exists.
The only thing SLS currently adds to the moon mission is that it allows the switchover between capsule and Starship to happen in lunar orbit instead of LEO. This is not very valuable.
Transfer of crew between Dragon and Starship, carrying Crew in Starship, Refueling Starship, even putting Starship in Orbit has all not been achieved yet, some of it isn't even seriously on the drawing board yet (crewed starship concepts are in concept stage at best).
SLS+Orion is ready to fly now, or at least almost.
> ome of it isn't even seriously on the drawing board yet
Citation needed.
NASA specifically called out in their report that SpaceX had done a huge amount of work on refueling already and they were impressed with the amount of detail.
NASA has also handed out contracts to study fluid dynamics of cryo and SpaceX got a contract to study that.
This is not some mystical thing. Refuling in orbit has been done for 50 years. Yes, its now cryo fluids but pumping cryo around in orbit is already required for upper stages, so its not really even that new or different.
And btw, refueling Starship is a required part of Artemis if you want to transition crew in earth or lunar orbit.
Also, if something as simple as transferring liquids from one tank to another is so scary, it's difficult to see how there can be any significant future for humanity in space. I mean, what human activity is not going to involve pumping fluids?
The only thing SLS currently adds to the moon mission is that it allows the switchover between capsule and Starship to happen in lunar orbit instead of LEO. This is not very valuable.