Seems to me that the problem isn't marriage per se, but atomic families. I assume that many people would prefer "spend 50% of time taking care of 4 children, then have 50% free time" to "spend 100% of time taking care of 2 children, no free time". If your sister lives the next door, it's easy to arrange. If you have good relationship with the neighbors who have children of similar age, still possible.

The article is in my opinion rather stupid. It essentially suggests putting kids into institutional care. The author probably never heard anything about what typically happens to children in such institutions. (That's the charitable assumption; the uncharitable one would be that the author just doesn't care.) My Facebook friend list happens to include a person who frequently interacts with such institutions, and after reading all the horror stories, I think almost anything is better than the institutional care; except when the child is abused at home (and I don't mean "microaggressions" or anything like that).

When a kid is in school, one teacher controls 20-30 kids. That is an efficient system, and the teacher probably doesn’t mind the work.

As a former teacher, let me say emphatically: Fuck you!!! The school system only works when the parents gave the kids good upbringing. Otherwise, it quickly becomes dysfunctional. (That's why having classmates from good families is so important when choosing a school for your child. Those will influence whether your kids will be allowed to learn anything at school.) And now we suggest removing the parents from the equation almost completely.

My best guess is that 75% of kids are damaged by bad parenting. Here again I am comparing it to some sort of co-op arrangement in which the kids are never the captive victims of a drunken parent, a stupid parent, a violent parent, a mentally disturbed parent, an unreasonable parent, a too-demanding parent, and so on.

The only problem here is how exactly you put together those 75% of bad parents and turn them into a Friendly co-op. How the people stop being drunk / stupid / violent / mentally disturbed / etc. just because you sort them into groups. If you answer this, we could solve so much social problems -- just sort people into groups, and it's done!

If you don't want to take care about kids, use contraception. Or be strategic, and find trustworthy friends who want to have children at approximately the same time, and would like to share the time with them. But if you rely on institutions, you are an abusive parent, in which case it would be ethically better to not become a parent.