Is it just me that thinks it's least possible that so much tablet time might make their brains a bit... mushier?
Now... I'm not a doctor, so what do I know? But these little critters are the ones that are supposed to put us up in the nice "retirement communities" when we get old. The ones with the cute nurses and the good food.
They will eventually need to get a job, be able to make change, and function in the world.
Now, I could be wrong... but if you think screen time isn't a big deal, then just walk up behind your munchkin and turn that tablet off without warning...
Good luck with that :)