These are becoming more common. The individual fittings are more expensive, and the tool that compresses the fittings are very expensive. But the time saved can make up for it. Alternatively the steel pipe would be cut to length, then the threads are cut on-site, joint compound applied, then threaded into place. Care has to be taken to place pieces in the correct order. The compression fittings have a built in gasket so there's no need for joint compound and threading. I expect to see more and more of these types of fittings.