We can send small probes to image the moon in incredibly high resolution. It's a big place I'm sure there is a perfectly flat rock somewhere they can use.
Have you ever seen a perfectly flat rock anywhere on earth? One capable of supporting a large rocket? Also, the moon doesn't have the various navigation systems (GPS/radar) that is used when bringing rocket stages back the pad.
We can send small probes to image the moon in incredibly high resolution. It's a big place I'm sure there is a perfectly flat rock somewhere they can use.