There are a lot of uses but one thing that is important to keep in mind is that progress in the full range movement tends to translate very well into the partial but not the other way around. As for the emphasis, it really depends on your position starting position and the range you are working through. That said, there are so many muscles involved in the fundemental pulling movement that even just the lockout portion is going to activate the entire posterior chain from the neck/traps through the back and into the glutes and hamstrings (I'd imagine into the calves too and certainly the arms and shoulders to a degree). One of the benefits of working hard and progressing on fundemental movements is that they drive full body growth and progress in your other lifts.