Imagine you come across a society that categorizes people by their finger length ratios. They say if you have a longer 2nd digit your race is 2D, longer 4th digit your race is 4D.
Newspaper descriptions of people frequently say if they are 2D or 4D, especially if crime is involved. Job applications ask if you are 2D or 4D. There have to be laws banning 2D and 4D discrimination because it's so common.
You tell them it's crazy that they spend so much time worrying about 2D vs 4D. That it hardly matters! In return they tell you of course digit-race exists! You can easily measure it, and it's partly heritable. In fact it's scientifically unsound to ignore digit-race because it correlates with so many health issues [1].
Your cries that those health issues would be better understood with other ways of thinking about populations are ignored.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5296424/