This works for devices that are primarily communication devices, i.e. ~2008-era phones.
Today I use my phone to browse the web, check the weather, read the news and tweets, trade some stocks, post a few pictures to facebook, and maybe send an email or text. Oh, and occasionally make a phone call. Of these, only 3 activities are 'people'-centric. The rest are activity-centric and apps are the modern smartphone's encapsulation of an activity.
