I think the context for limiting "screen time" is very important. For example, I'd have no qualms limiting my future children's time on the television. However, I'd actively encourage them to spend more time on the computer, especially when they're making things.
I find it interesting that the mass media groups computers, phones, and televisions together, when, in reality, vastly different things are happening on the different devices.
I am not so sure. Playing a game on the TV is equivalent to what my kids do on their smartphones. Now, because their smartphones are Internet connected they do end up discovering new ways to entertain themselves and more importantly research topics they are interested in. However, most of the time spent is still for entertainment.
I find it interesting that the mass media groups computers, phones, and televisions together, when, in reality, vastly different things are happening on the different devices.