So that's actually not true, but for reasons that I think are weirder and more interesting than anything implied by either side of this "debate."
There are actually about 50% more women who have Y chromosomes than originally expected, and also: microchimerism seems to be extremely common in people who give birth, seemingly regardless of whether or not they give birth to children with XY chromosomes. But the genetic remnants of fetuses that have XY chromosomes stay in the body for many years (possibly a lifetime), and this has a fairly significant effect on genetic composition.
I get what you're saying and I don't totally disagree, but I think the main thing that I keep learning is that "biological sex" is just not actually a particularly meaningful concept.