Well, the point is that national origins (=ethnicity, race) matter. Where precisely you draw the line is a different question. Keith Woods just proposed excluding all Third Worlders, but as someone points out in his Comments, there are some low-crime Third Worlders e.g. Japanese.

Ireland is part of Western Europe, so the 1924 system didn’t impact it at all. Marco Rubio is obviously white—his family originated in Spain and Italy. Americans tend to think that all Latin Americans are mestizos, but that’s just not true.

A more honest way of capturing the National Origins effect would be to go directly to race e.g. prioritize white immigration, but the political culture apparently can’t handle that right now.