The actual reason probably has to do with cost. Assuming a moon base has been built, it is massively cheaper to achieve orbit from the surface of the moon than it would be do to it from earth. The first stage of a Saturn V produced 7.5 million pounds of thrust each to leave the earth. The lunar ascent stage produced 3500 pounds total.
Even better, do all the refining on the moon, and you don’t have to waste cargo capacity carrying a bunch of useless rock to earth’s surface.
Yeah, from a PR standpoint it’s a win too, but I doubt it’s the main motivation.
