It's happened here on Earth.
Many of the large mines (Canada and S. Africa come to mind) of platinum and other metals here on Earth are the result of asteroid impacts. To say this isn't the case on the Moon, when most of the lunar surface is unexplored) just doesn't make much sense. Even the lunar regolith has vast amounts of aluminum, titanium and other assorted metals. All of which are going to be of major use in building space infrastructure.
It wouldn't take much funding to send an orbiting probe to fully catalog the buried resources. Until then I say keep an open mind.