A good Moon base should for sure be bigger than an orbital outpost; unless we have an awful lot of traffic there, on the orbit around the Moon... but we're not

A good Moon base should for sure be bigger than an orbital outpost; unless we have an awful lot of traffic there, on the orbit around the Moon... but we're not there yet. However, to completely avoid having a Moon orbiting facility would be to err to the other direction. Suppose, for example, you have an emergency on the Moon. If you need to fly to Earth, it's easier to meet an Earth-bound ship in the Moon orbit than to have that ship landed on Moon; reminding, SpaceX lunar ship isn't intended to fly to Earth, with good reasons. Or if you need an urgent delivery of something unique from the Earth, it's easier to deliver to the Moon orbiting outpost, rather than to have it with Moon landing capabilities. If you need delivery of materials from the Moon, a convenient place is to accumulate them in orbit; Earth's history of sea shipments suggests that. Of course there could be other reasons. Size of Starship doesn't really matter - Gateway could be smaller, and still quite useful.