It makes sense if you want to use the rockets you already have instead of building the absolutely titanic rockets you would need to carry everything in one trip

It makes sense if you want to use the rockets you already have instead of building the absolutely titanic rockets you would need to carry everything in one trip. There are metallurgical limits to just how big you can make the rockets as well. But this isn't necessarily advocating for a full time in-orbit refuelling station either. The plan might be to instead launch 2 or 3 rockets, 1 with the stuff and the others with fuel. They meet up in orbit and the fuel rockets refill the stuff rocket so it can go on to Mars or wherever, then they return to Earth for the next mission.