This is an extremely narrow view of college-bound seniors that most admissions officers, thankfully, do not take. It assumes that students know exactly what they want to do from age 13 or 14 and follow a neat, orderly path from middle and high school extracurriculars to college interests and majors. There are lots of students who love to write creatively or do art projects and want to major in science; there are lots of students who explore science fair projects and scientific inquiry and end up majoring in the humanities. And on top of that, most savvy counselors know that students change their mind between application time and enrolling time.
That’s the reason why many top colleges that don’t have separate undergraduate divisions don’t admit by major. It doesn’t matter, and the FAQs for a lot of Ivy League and other elite universities will say that straight up.
There is no data to support this, and no reason to believe that this is true.
Or we could just stop using the term “STEM” altogether, since when people say “STEM” what they really mean are engineering and computer science in most cases. People are rarely talking about biology, chemistry, and psychology.