They aren't fully functional without fast connectivity, but they aren't useless. It is shocking how many ways apps break when offline.
- If I'm offline I should still be able to view the last weather report I got. Many apps simply refuse to work and throw up an unhelpful "you're offline" screen instead.
- If I'm offline I should still be able to type out a reply to emails. In fact, I should be able to queue it for sending, and my device should intelligently take care of it at the next connection opportunity.
- Similarly, if I'm offline I should still be able to view emails that I have seen recently.
There are a lot of ways people can interact with apps while experiencing no/poor connectivity. I believe the essay is simply saying that some basic affordances should be built into your apps - that features which don't strictly require a network connection shouldn't fail in ugly ways when the network is down. It is atrocious how many mobile apps have only one reaction to a loss of connectivity: completely shut off all access to everything.