Wile all of these might be true, the results heavily depend on your kids age and temper, and the grand parent’s age and physical abilities.

The sleep deprivation and constant attention needed in the first months can be pretty tough for people not in their prime anymore, for instance.

In ye olde days grandparents were much younger. Parents had children in their 20's putting grandparents in the 50-60 year range by the time grandchildren are born. Still plenty able in that age range so it makes sense. Now parents are having children in their 30's pushing grandparents into their 60's and 70's.

Typically when 'satellite babies' happen, it is because both new parents work, and the grandparents are likely retired or have more flexibility in their work schedule due to seniority.

They're not in their prime, sure, but they have more free time (and experience).

I agree it can work. I'd just advocate to be careful, as parents tend to forget the reality of it, especially decades later.

Experience sure helps, but it's not a silver bullet either. We had our grandparents come to help for the first born, just to send them back because they were getting tons of germs and the lack of sleep was killing them. Two years later it was a perfect match and they really enjoyed taking care of the kid.

It's likely grandparents and extended family have been involved in child rearing for most of history in communities, but doing this remotely hasn't.

The end result is likely that they're not your kids in more than a biological and economic sense if you don't go to lengths to be involved in your childs life (more than) daily.

I don't think that is western chauvinism, but rather universal developmental psychology. It will be (for lack of a better word) interesting to see studies on this.

They also have a lot more time on their hands.

They also have childrearing experience.

Wouldn't they have had their children raised by their parents?

No, because they didn't grow up in a world with as much international migration.

They did childrearing in collaboration with their own parents.