Email is an impersonal, asynchronous medium.
If a recruiter is open to being asked questions about why I was not hired, I would especially like that opportunity to ask them in a live phone call.
Scheduling a call seems miles more considerate than ghosting. For crying out loud.
It is important to cultivate and maintain relationships with good recruiters throughout one's career. Recruiters themselves are used to being ghosted, abused, and maligned. It only takes a modicum of humanity for me to respond to a legitimate human recruiter that I am not currently seeking opportunities or this is not right for me. Reciprocation is certainly appreciated in all cases.
Reflecting on the OP's situation, may it perhaps be the case that the recruiter scheduled this call in the eventuality that it turned into a job offer? Perhaps they won't schedule it right away because they need time to come to a decision, and they're going to deliver that decision via phone to you whether it's a "yes" or "no".