Boredom is also a source of risk of doing something just that anything changes.

The better solution is experimenting instead of being bored or chasing a hit. That with proper design and risk analysis.

When I’m bored, I’m apt to decide to upgrade something in my lab environment and break everything.

Yes, but it's also true (or even more true) for children. So it's OK for a kid to get bored while their parents are busy with something, be it their phone or anything more valuable.

I don't know whether it's okay or not. A teenager is more likely to be able to spend that downtime on something useful. Children, not as much. Whilst, I understand - more than most people - that we need alone time, I think that parents spend a lot more time on their phone, be it facebook, reddit, twitter, instagram etc, than they would like to admit.

I am sure they could sneak - if they already don't - some time on social media while the kids are playing on their own. For a kid, time with their parents is integral for growing up and having a healthy relationship with them. Most kids however don't get to experience it.

Additionally, time spend on facebook and social media has correlation with depression and stress. I don't think this is the best environment for a kid to be brought up.