Some people have short memories. Many of these grans are probably of the generation who sent their children out to play from age 2 or 3 and didn't see them again for hours! It was the older child's job to look after the younger ones.
Or, if they were taken to the park, they had a book and read/chatted with friends while the children played.
Motherhood is, at times, boring as batshit. And freakin' constant 100% of the time.
Socially speaking, we are more isolated than ever before. Even with social media etc. 50 years ago we knew our neighbours, usually had parents nearby, and generally believed in the concept of 'a village to raise a child'. Between women who are working themselves to the bone in full time jobs and dealing with parenthood, to SAHMs who are with their children 100% of the time and don't have enough familial or community support to even be able to go to the doctor or dentist by themselves (let alone do something actually recreational), if I need to look at my phone to give myself five to 10 minutes of time out, when I know my child is safe and most likely having fun (eg. at the park) then so be it.
As a generation of parents, I believe research shows we are spending more time with our children then ever before.
Take that, judgemental grans.