What I have expressed is that any system I must use at work (HR, expense reporting, JIRA/Teamcity) should be usable on mobile. But the state of the art in many areas is applications that are barely usable on desktop: Workday's app was Flex for a long time, and is now HTML5, but either way the recommendation is still "just keep reloading until it doesn't hang".
We had a perf review system that seemed to have build a buggy PDF editor with a browser native plugin (flash maybe? long ago) that was impossible to use except on an old version of IE on Windows, and most of us had Macs: what you wrote would scroll off the page in one direction and scrolling was one-direction-only with no scrolling back. It was absurd.
So my guess is that Susan Peters is poorly summarizing the idea that millennials have higher standards for the apps they have to use (which I find intuitive at first glance), and 'on mobile' is a proxy for that desire, mangled by a game of telephone.