Reading all these stories, it's apparent that everyone's circumstances are different.
Different babies, different sleepers, different needs, different feeding methods, different sleeping arrangements, different jobs, different sleep deprivation thresholds, different abilities to nap, different abilities to get back to sleep in the night, different household and financial arrangements, different mental health considerations, different workload splits, different shift taking between partners.
Therefore I would say, YABU for getting cross for a generalisation when actually there are so many factors at play. Each family has to come to a suitable arrangement.
Saying that, YANBU to be concerned that the primary carer is getting taken advantage of, and to be looking out for areas of inequality and calling them out as you see them. It's good for women to watch out for each other for a change.
During my sleep deprived hell, I remember pondering that baby sleep is a bit of a feminist issue, and that if men bore the brunt of the sleep regressions and constant wakings, then some technical solutions would be found to help everyone get more sleep!