Hi OP. I admit I have not RTFT, but I've read your comments. I just wanted to give my perspective as someone who was a SAHM to 4 DC (and still am) and they are now 19, 17, 15 and 12.
As I remember, I did do all the nights. I think it started because I was bf so there was no point in DH getting up. Then a pattern just emerged from there.
I'll be honest, it never really occurred to me to get DH up. With the first baby, I would say I was ok and I adapted to sleeping in two / three hour stints, night and day. No I wasn't at my sharpest, but it was enough. I only had a baby to focus on and had lots of other friends in the same situation so that became the norm. I didn't have to deal with actual adults and work deadlines, so I just accepted that feeling a bit zombified was part and parcel of it.
Where it does get more tiring is with the second, third and fourth babies as you have to get them up and out for school etc and you can't just follow the pace of one baby. That's when it gets more tiring. But also, I think you get used to broken sleep by that point. What I always did, was whenever I did have any downtime, I made the most of it.
Having said all this, I never had kids with chronic sleep problems or anything like that. When one of them was ill, DH would inevitably get involved.
Even with teens, I still don't sleep past 6 because I physically can't. I'm 48 now and maybe in peri-menopause and I think this I'm often waking up at 4am these days. Su sorry to say, it isn't just babies that affect sleep patterns!
I think it really depends on individual couples. Everyone is different and some people manage in less sleep than others. My DH had an extremely intense job and was also often overseas so I never relied on him in that way. But had he just worked a regular 9-5 in an admin job or something, I think I would have had different expectations.
There are no hard and fast rules basically. Ok, I was a bit zombified for a few years (well, maybe a decade!) but at least I never had to worry about money or deal with difficult people at work. Nor did I have work deadlines imposed in me. Nor did I have to 'look professional' or live my days to anyone else's schedule apart from my own and the kids.