I think it's because it's touted that way. Men who are pro-patriarchy or toxically masculine are kind of notoriously prestige selfish and love to narrow the playing field of women because their perceived masculinity is threatened by any notion of equality.

This is why my local game shop holds girls nights for Magic the Gathering. It's not that women are inherently worse at the game, it's because the open play harassment and terrible behaviour drives a lot of women out of the hobby before they have the chance. Trans women are absolutely subject to this same misogyny because they represent to these douches the same threat. They can never be allowed to be proven superior in any fashion because of all the mysoginistic /transphobic beliefs that they are mentally ill and/or weaker because they do not agree being bearded chest pounding ape children is the apex human form. The prize of prestige must be protected from falling into the hands of someone who will "immasculate" them so they rig the fucking game so their precious dick wagging contests never damage their fragile masculinity. To have someone who isn't masculine win is to damage the prestige itself.

Chess champions get treated like geniuses so of course this particular psychosis applies.