I was babysat now and then by a 85 year old great-grandmother.
Rising parental age is a catastrophe, but not for this reason.
Meanwhile some of our friends with late 50s/low 60s parents are able to fully entrust their kid to one of the grandparents and go out for date nights/weekends. My wife and I are able to somewhat compensate for the lack of family help by throwing vast sums of money at the problem, but not many parents can do what we do.
Society messed up big time by allowing late parenthood to become the norm. It's really going to hurt future generations, but it's already making my generation shy away from having kids.
We also do this, but in our case the reason is further complicated by the fact that both of our mothers passed away some time ago, and so the kid has no grandmother. She just has two grandfathers, one still working and the other retired but incompetent at child rearing (never really did it with his own kids).
I wonder if cases like ours would have been easier (without money) in a tighter community. We live in a large apartment building in a big city. We live super close to our neighbors, and yet people barely even know each other. I imagine if this was a small village, people might know about our situation and be eager to pitch in (and of course we would do the same for others).