I wouldn't put much stock in random quick hot take replies. Actual partners going through this are likely discussing it privately. As you surmised, one could easily see why a husband might feel extremely hurt to not be chosen to be in the room. But if the wife only had one choice, a mom, sister close aunt, midwife etc. who has given birth seems like the most logically sound choice - they can provide emotional support and personal experience of the medical event. Thus I would rate mom/relative > husband as a fair choice that the husband should learn to accept.

For women who want to do it completely alone, I'm not sure I follow. Childbirth is pretty personal and puts you in a vulnerable position, but having a partner does mean you decided to share your life with them. I don't have a partner but I wanna say there might be something wrong in your relationship if you don't want them to be there to support you and you didn't have anyone else available. (Of course there are exceptions like if the woman is trapped in an abusive relationship.)