> We didn't get to the moon with a refuelling station did we?
No. We did it by throwing away ~98% of the vehicle on the way there.
> How come we need one now?
Because building a new gargantuan tower and tossing that majority of it into the ocean/deep space every time we need to go the moon is not sustainable.
> We're really seeing 15 starship launches per moon trip as reasonable, rather than just building a single trip program
Yes. Because again. The alternative (dictated by physics) is that we expend the whole thing.