I love the shocked Pikachu face when I show up at someone's desk, let them know their laptop is part of an ongoing investigation, and IT will be by soon to give them a new one.
Just one of the many ways that dual-use is becoming more common. And OSes are increasing their abilities for it too. Mobile OSes are already great at separation. Windows is coming along slowly with Windows Information Protection and Azure Information Protection. Mac has user enrolment but it's in its infancy, sadly.
You can also be compelled by the courts to surrender a device that holds information relevant to a civil or criminal matter. For example sending text messages to a coworker on your personal phone about how you are going to coordinate your efforts to block someone's promotion.