The context of the GP post is getting back to a recruiter to find out more about a job, which suggests you're at least interested in that job. If you are interested, you need to be at least somewhat accommodating.
Yes, they reached out to you, but now you're getting back to them? Why are you doing this unless you're interested?
If you're not interested, either ignore them or send a polite decline.
Expressing interest whilst simultaneously coming off as difficult and entitled does you no favours.
Recruiters will often have a bunch of people who get back to them to express interest for any given role and will, in addition, be responsible for multiple roles. Having a quick call with somebody is generally quicker than responding by email, which is probably the main reason they ask for a call. Doesn't mean you can't do the call at a time of mutual convenience - that's obviously fine.
> Moreover, unless your business is basic webdev or your skill requirements are very low, I have a hard time believing you are turning down lots of candidates. It's brutal out there for those trying to hire. This is definately not a buyers market, it's a seller's market. It may not be for long, but that's the current situation.
That might be true in your market: it is not in mine. You are, of course, entitled to believe whatever you'd like to.