They already have this. It's called guided access
That’s not really the same. Guided access locks you into a single app. This post was suggesting locking them into a specific home screen with a selection of kids apps.
Personally, I want to see user accounts like they have on Android. Let me create a kids account that has all of their games, educational stuff, and Netflix kids profile.
People don’t want to buy one iPad for every person in the house, though I know that’s what Apple would prefer.