You can give priority to people who have integrated into the society in several other, more obvious ways. In this case, they are making the explicit argument th

You can give priority to people who have integrated into the society in several other, more obvious ways. In this case, they are making the explicit argument that they want "more skilled" workers, and using a US-based degree as the criteria. If they had a points system, and a Masters degree would get you X points, and every year spent in US would give you additional Y points, then this would make sense.