I get where you're coming from, especially since role playing was so vital in early models in a way that is no longer necessary, or even harmful; however, when designing a complex system of interactions, there's really no way around it. And as humans we do this constantly, putting on a different hat for different jobs. When I'm wearing my developer hat, I have to reason about the role of each component in a system, and when I use an agent to serve in that role, by curating it's context and designating rules for how I want it to behave, I'm assigning it a persona. What's more, I may prime the context user and assistant messages, as examples of how I want it to respond. That context becomes the agent's personality--it's persona.

Spot on