This assumes only positive externalities. The problem with things like Candy Crush is that there might be a net negative for the user in the highly engineered feedback loop.

Finding ways to waste time isn't unique to computers - you could subscribe to a newspaper because everyone else does, but only look at the sports results or the crossword. For that matter I can read books abusively as well as informatively - computers aren't the cause of people wasting time or making bad choices. You could argue that they are more highly engineered to keep people making such choices in the name of profit, though. Admittedly people have leveled the same critique at novels, and they're not entirely wrong.

Now I agree that most people actually get more real use of out their smartphones than just playing games, but I do also agree with the top post that we encourage people to spend their money powerful pocket computers and then frequently those devices end up as conduits for advertising to buy more stuff.

It's not that people are bad for playing Candy Crush, but that we're glorifying the people who make Candy Crush because of their ability to cash in, while many other worthy smartphone projects go underdeveloped/underused because they don't have a billion-dollar story attached.

Facebook has an army of phds whose only goal is to make sure Facebook’s users spend another few percent of their time on Facebook. And Facebook with its social interaction, and in depth knowledge of each user, can actively drive its users to spend more time on it in ways no other medium has been able to so far.

And it’s not just Facebook. It’s oretty much every tech company, barring maybe Apple.

Now that happens everywhere. Use levels of TV vs smartphones aren't close. The comparison is simply absurd because of the nature of the technology.

That's not even taking into account addictions and misinformation.