But saying that it's the most compelling argument is where it arguably becomes full on sexist.
Truth of the matter is most concert pianists and serious competitors have absolutely gigantic hands that most people do not posses. With very few and rare exceptions.
And that the current piano size is way too large for most people, esp. if they actually would like to excel at it. Or at a minimum a very large portion of the population, incl. geographic areas where people tend to be shorter on average.