Personally, I am more concerned with the cumulative drop in productivity that will control for all variables including this one. Again though, sponsored clubs for a particular gender are a luxury good. If these initiatives were self-organizing it wouldn't be a problem. However, the implication here is they are not.
On a numbers basis the rules still apply: there are N members of this club. Each are paid an average of X dollars per hour. If the meeting is only an hour a week thats still N x X x 48 annually. Add in a food budget, perhaps bringing in a guest or two once and while. This quickly gets unsustainable as N grows.
The issue I take with this reframing is that it is once again Men vs. Women in this completely fabricated war in tech (and only tech). RTO is a negative for everyone involved. The division here makes it sound like, once again, women suffer more than men for an isolated reason, not considering that men suffer in a different but comparable way. Or they are quitting at a dramatically higher rate over the baseline RTO quit-rate (and "women with children" quit-rate across industries). The actual reason boils down to simple MBA spreadsheet math.
Productivity be damned, RTO makes fiscal sense when you have a 15 year lease on a building you can't get out of. I don't agree with it, but I can see why you'd want warm bodies in seats when you pay 20,000 (or more) a month for your modern-tech cube farm.
Women with children in other industries that have never had these luxuries are clearly doing something that women in tech aren't. The question I have is - what is it? Is the actual solution an economic one whereby we could once again afford to live on a single salary so someone is staying home?