I know this is true, but for serious tasks, I need the screen real estate. I'm amazed at what some people can do from a phone, but also wonder if they're missing things, of if it's actually inefficient.

Exactly. 96% of internet users use mobile phones. 62% use PCs.

Browsers and websites work pretty well on mobile devices too. Website != desktop only

That wasn't true before smartphones, everyone had a computer so they could access the Internet. Except maybe in developing countries - but the article is about the US.