I'd add sheer information gathering: even if the call leads to nowhere, they get a sense of how it's going in your company, salary data matched to a role, and a reality check on what they anticipated vs your actual situation.

I think it can be intesting to talk to a recruiter even if they have nothing decent to offer, provided one also enjoys just talking to other people. I just don't think it's an optimal path for anyone actually interested in a position, doing one's homework and applying to a company one's actually interested in can have better results.