GP is talking about how the design of iOS is preventing one from doing all those tasks in a satisfactory way, but not the hardware.
For example I could be editing a movie and waiting for it to export. Then I switch to a different app and start editing my photos. There is a Task Completion background API to allow the former to continue to run, but there is no guarantee nor any notification when iOS decides my new photo editing app is consuming too much resources and jettison or kill the movie app. It contributes to this nagging feeling of needing to switch back to the background app so that iOS would keep it alive.
It's just an app management model ill suited to professional work.