Should they not be?
We care (well, IMO) for our kids, but my wife and I continue to have our own individual interests and we do family or couple things that the kids would prefer we didn't.
Just because we could lavish our children with 16 hours of undivided attention per day (entire focus), doesn't mean that's healthy for the kids or the adults. The kids need to learn that they live in a collective world that does not revolve around them, and the adults need to have time and space to live their adult lives as well.
I don't think I agree with that premise at all. Even as an autodidact, I'd say that guided exploration/learning/endeavour can be far superior in almost every way.
I'd teach a 5yo archery but I'd never give them a bow-and-arrows and leave them to learn it without adult interaction.
A parent who spends there whole day with there kids has probably taken them out to experience environments away from home?
Do you really drop your 6/7yo off at the woods miles from anywhere with a handaxe and a box-of-matches and leave them to it for the day? Or give them a raspberry pi and a box of components with a soldering iron and go out to the shops? (Or how about a band-saw and some wood!). Or give them a recipe book and an oven-lighter and hope they manage to cook a cake rather than gas themselves and blow up the street?
They can mostly make a camp fire, but please instruct first on using the axe and knife, and check the fire isn't going to start a forest-fire before they light it. Sure, after a few times they know how to chop and cut, how to clear around the fire; but do they know about peat-fires, and think to check for over-hanging branches? They need gentle direction and oversight. But they can't even get to the forest without someone taking them, which needs a devotion of time.