Currently by law, immigrants from a given country can only represent 7% of the overall immigration flow into the US per year. That isn't explicit country-based discrimination, but it effectively discriminates against China and India. If China were 10 nations of 150M people, and not 1 nation of 1,500M people, more people from those 10 nations could immigrate to the US than can today from China.
If you have a limit that says "2 people per group" and you have groups with vastly different sizes, it can "seem" like discrimination. E.g. if you're from a group that has 500000 people, your odds of being chosen are much smaller than if you were from a group that had 1000 people. I believe the term is used lightly in that context, more as a point to the original poster's comment.
