In my experience caring for your small children is really demanding work. On the one hand you need to be focused on the situation in order to protect the children and on the other hand there is not much going on for entertaining yourself.
Creative or focused deep work where you get a positive feeling of accomplishment also counts as a break from childcare for me. So a break does not necessarily mean not working. But I believe there are a lot of demanding jobs that are not a break from childcare.
The other aspect I can relate to is the fact that in hunter-gatherer communities many different caregivers support each other. Every summer we travel in the mountains with 3-4 other families and their kids. Last year there where 12 kids under the age of 8. Sounds very stressful but actually it was really smooth. Having multiple parents available all the time allowed everyone to take a real break once in a while. And also the children enjoyed having multiple different adults they could interact with apart from their parents.
So I really think this concept works, but only if you all live under the same roof. Which in practice is only possible during holidays.