This seems to suggest that modelling people (who may be agents) as non-agents has only positive consequences. I would point out one negative consequence, which I'm sure anyone who has watched some schlock sci-fi is familiar with: you will only believe someone when they tell you you are caught in a time-loop if you already model them as an agent. Substitute anything else sufficiently mind-blowing and urgent, of course.

Since only PCs can save the world (nobody else bothers trying, after all), then nobody will believe you are currently carrying the world on your shoulders if they think you're an NPC. This seems dangerous somehow.