Even with the most supportive partner you may be doing a lot of the work. When you think about picking kids after school, doctors appointments or even dealing with a tantrum usually women will do it straight away. As time goes by their partners will then expect them to handle it. Also, after 4-5 years your husband may be earning way more than you. Which means that you will be expected to always step back professionally and take days off to handle the child.I think this says a lot more about the type of person your friend chose to have a kid with to be honest! What a waste of space. To give my partner credit I do think he’d be a great hands on dad, but even so I still think there’s this “unwritten rule” that the lions share of the childbearing goes to the mother. He would never act like this hole your friend is with but I still worry that the day to day stuff would fall with me while he goes to work. I already do much of the cooking, cleaning, laundry etc - and can see myself getting so resentful of me looking after the kids while he chilled on the sofa after a “hard day”. I know if I asked him to help that he would 100%, I just don’t like that I’d even have to ask. Women shouldn’t have to be the default parent!
I have seen it personally with my parents. They decided to have my brothers and I early because they both had good earnings and the house was paid for. After a few years, my mom asked my father to be a stay at home dad since she earned more than him. He tried for a while but his job kept ringing him to come back (he is the Head of a school department). It ended up with a divorce because my mom kept asking him to take charge of the household too but he refused to focus on his career. My mom's career took a massive hit while my father's salary is 12 times the national average.
Two career oriented people can not manage a household with kids because you need at least one who is willing to take a hit professionally. Like they say "There can't be two captains on a ship.".