I do not know how often this pattern is found but I have heard of it on more that one occasion. Maybe men make it up to point the sexist/anti-family finger at women but in a way I can sympathize with the women who vote no. If they view themselves as having sacrificed to be successful. it is human nature to expect the same of others. Maybe not fair, but human nature nonetheless.
The second idea is that I am confident that a more subtle version of this anti-family bias exists in the case of men. Before my kids were born I tended to write and prepare at home at night and on weekends. Most holidays were spent at work. If I got home at 9:00 PM because I was chasing down an idea or finishing a chapter it was fine. Stay up till 3 A.M.? That was fine too. Just sleep in. When two kids came along (and then a third) the choice was clear. If I wanted to be part of my kids' lives there would have to be coming home for supper, bedtime reading, helping with homework, building things with blocks, racing slot cars, rough housing, soccer, T-Ball and baseball, building Lego castles or free-styling, giving baths, sitting up at night, doing family things on weekends and minimal traveling to conferences. Every person with kids under the age of 10 knows that you cannot work and be in charge of the kids. Trying to will make you crazy. And I was a Dad with a stay at home wife who did most of the work.
I understand this is still far less than the demands on female faculty with children (although I do think a stern talk with their husbands may make as much sense as a talk with the dean) but children force even men, except perhaps the most efficient and the most talented, to make a choice. In fact, for men like me who are not in the most talented or efficient ballpark, losing the extra hours is even more critical. I could see it unfold but for me the choice was easy, I assume, in part because it was not as big a choice as women make. But the problem to some extent lies in the nature of the job. Law teaching and especially writing is not like a limited space or limited time exam. Those who have more pages or unlimited time will write more and do better professionally. If we had 8-5 jobs the playing field would be a bit more level for men and women but that is not the case. Should anything be done? On this I am not sure. An economist would say that we all make the best choices we can. (As I have written a number of places, I think that is only partly true but let’s pretend that it is true so I can add my final thought.) Presumably the dads and moms not spending time with the kids and the no-kid-workaholic men and women opting for writing and its rewards instead of yachting or belly-dancing lessons or wood chucking or pasta making make hard choices and lose something pleasurable in the process. In a not-limited-space profession, it’s inevitable.