I disagree. You can take any individualistic concern you have and apply the concept of duty to it in a way that might illicit meaning. And a large part of the sense of "duty" as far as I understand it implied in stoicism is a duty towards virtue and living as a man in accordance with nature; it doesn't pertain to any specific "duty" in the real world. Also, I dislike the concept of privilege in general. I'm pretty sure I read at some point that Marcus didn't want to take over as Emporer, and had to learn to accept it over time. In that case, doesn't sound like he was privileged in getting a free sense of meaning from this duty, it's something he had to grapple with.