Further to the truism that constraining and micromanaging kids have driven up smartphone use: adults do this to themselves too, particularly parents. Watching kids can be fun, but then again, it can be incredibly boring most of the time. You're not going to constantly ask banal questions; kids will often be creative on their own. But as a parent, you're compelled to hover. And hover. And do nothing.
Probably having more of a "village" to help (grandparents especially) would relieve pressure. Also, multiple kids will engage with each other more instead of looking to parents for all social stimulation as only-children.