Well to be more precise they're saying that "use-cases like multiple family members sharing a single PC" are quaint - by contrast with "the modern era of cloud

Well to be more precise they're saying that "use-cases like multiple family members sharing a single PC" are quaint - by contrast with "the modern era of cloud computing and IoT". A charitable reading would perhaps count it a fair observation that an increase in computing ubiquity has led to most machines, even workstations, being single-user.