Yes, that's a fair point, it's part of their job to spend time in calls.

Ironically this gives me even less confidence that I would be interested in what they offer. Maybe the mere fact that they conveyed the offer and spent an hour in a phone call is all they wanted actually?

Maybe I'm just being overly pessimistic on the matter though.

My read on it, roughly in priority:

    1. Getting you on a call (anyone, not just recruiter) is a way to drive the interaction to a conclusion, one way or the other.
    2. Getting you on a call gives them the opportunity to read you.
    3. Getting you on a call gives them the opportunity (if they are of the type), to make you feel a social obligation to reciprocate (information, time, etc)

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.

Sales people are trying to discern what pain you are facing, your level of urgency for solving that pain, the consequences if you don't solve it, your budget, and your authority to make a purchasing decision.

SDRs/BDRs are often compensated by a "meetings set" goal. They may linger on the phone with you if they think you will agree to a meeting with an account exec. But outside of this initial marketing outreach, effective sales people don't want to waste their time with you. Much more so than engineers, they are measured and paid on objective results and specific productivity metrics.