Disclaimer: my son sees his grandparents plenty, childcare or not.
But I think your wager is a very common one on MN, and it completely ignores the reality for modern parents (and indeed most parents throughout history).
Small children need, at the bare minimum, someone supervising them at all times, even if that means sitting in the house as they sleep.
Two adults who could more or less either be where they wanted, do what they wanted or else be working suddenly have one of them (or someone else) available 100% of the time, no exceptions
In those circumstances, it's rather silly to complain that grandparents "only get seen for childcare".
Well, duh. That's been a norm for millennia - it's a sudden invention that grandparents get leisurely visits in all the ENDLESS FREE TIME that parents DEFINITELY HAVE AVAILABLE.
I'm very glad that my MIL doesn't fuss about having me sit around when she visits but encourages me to take time out and enjoy myself or get things done. It's my husband who needs it pointing out that our to do lit vastly exceeds our available time and that if our son is enjoying himself with his grandparents then it's a win all round.