I tend to agree. The fundamental premise of this thread is that the mental load, which sits on top of the physical work, is what makes being the primary care-giver so hard, and a lament that the 'breadwinner' role doesn't a) appreciate, and b) contribute to lifting that mental load. There seems to be a sub-plot about those roles also being more likely to be associated with males / females and whether this substantiates the hypothesis that all men are shit.
In reality, 'parenting' is no-where near a full time job. Yes, there's a couple of years between new-born and weaning where the workload is really intense and requires adult attention every 2 hours. But the total time committed rarely exceeds 6 hours a day - babies sleep for the other 18. Toddlers are also tricky, but they still sleep for 12 hours a day. By the time they reach primary school age, half their waking hours are in school, and for the remainder, huge swathes of time are spent in the back of the car, or watching TV, or playing by themselves. By the time they reach secondary school, it's quite possible to go days without even noticing them, other than by the trail of dirty clothes and the empty fridge. And in families with multiple children, much of this can be done concurrently - it doesn't take any longer to order an online shop for four than it does for two. So taken over a two-decade commitment, the time burden reduces substantially and the physical work gets much easier, very quickly. But the mental load never diminishes. And as almost everyone has said ... it is indivisible. Contrast this with a full-time role - including commuting, 12 hour days are commonplace. The workload seldom reduces over time, and the mental load it imposes increases with seniority, rather than reduces. Over those same twenty years, I'd estimate the total time at work is triple that required of a stay-at-home parent, and depending on the seniority and pressure of the role, the mental load is probably four times greater. A subjective, not a scientific assessment, granted, and I'm sure others will have differing experiences and perspectives. SEN and disability will certainly increase both the physical work and mental load for care givers in that scenario. But so too will differences in the bread-winner's day job. A schoolteacher will have different capabilities and opportunities for contributing to the home-making than an offshore oil worker or someone on night shifts.
But there's some posters who's immediate retort will be "but what about the person parenting and holding down a full time job"? Yes - that's going to be harder. But it's a choice. And, if that person's capacity to work at that rate is exceeded ... then it's a poor choice, and one they really shouldn't be making. It's really not that vital for the survival of the species that feminism requires women to hold down a full time job as a marketing director or a dental hygienist whilst raising two kids. It's OK from mum to be a stay at home parent, just as it's OK for the dad to be the stay at home parent too. It's a pity that more couples don't pursue this alternative where the woman is the one with a comparative advantage. I'm told it's statistically more likely to be that way ... so why doesn't it happen more often?
The final retort is "well, why can't both parents work full time and share the home-making?" I think this has been covered by the description of mental load as being indivisible. There's also the matter of timing - it's not what needs doing, but when it needs doing. A 3pm school pick-up is challenging for anyone working full-time - it just becomes doubly challenging when alternated between two people both working full time. I really don't think there's any obvious synergies from sharing the home-making between more adults. It's probably the same reason why Co-CEOs are rare. I'm sure it's not impossible ... but there'd need to be lots of other favourable tail winds. Which brings us back to the start of the thread. It makes economic sense for there to be a division of labour. A couple where one acts as the breadwinner and the other as the caregiver / homemaker will, in greater likelihood, be better off than any alternative arrangement. That is why it is popular and commonplace. And the sex of the partner in either role has nothing to do with it.