It's not to "discriminate," but rather to celebrate the fraternal comradery of fatherhood specifically. If you'd read the article, you'd note that they took that question and addressed it very well by stating they appreciate the "man-cave" atmosphere of the group. This is an online gaming community, and are in no way obligated to be P.C. or subject themselves to mitigation/judgement by anyone narrow minded enough to attempt to force the hand/issue. No one is required to join, and if you'd like a group for all "caregivers"/parental figures, then start one. Just know, you're subject to speculation by babysitters and grandparents being offended by not being included. (And then educators, tutors, or anyone else that was excluded. Then people without children will want in...)