Well, if you think about it, would you lug however many tons of metal from wherever to Earth, or spend a lot of time and money creating places you could smelt and smith huge amounts of metal from different deposits or whatever when you could just use the stone and dirt that's already there and that you can make shit out of much easier?

Stone structures require a lot less infrastructure. Just a lot of people.

But I don't get what that has to with the sinkhole. The sinkhole: that's probably what we should be worried about. You know, the second sinkhole. As in, this could be the beginning of a pattern.

A robot pattern. Or maybe not.

[What Starbuck means is: definitely robots. It was robots.]