>why isn't this mentioned by American republicans today
Because boomers are still a significant voting bloc and they universally believe the "back to back World War champs" narrative. Regardless of how otherwise based a boomer could be, he'll still tell you that the good guys won the war.
It’s because otherwise they would have to admit that they sailed across the world and lost friends to kill innocent people just for America to get flooded by feral niggers and pajeets.