I've worked at, hired at, and consulted at many companies. I've never once seen an HR department be incentivized to interview people just for the sake of interviewing. At my last two companies, recruiters are measured on the number of candidates that end up being extended an offer, and are negatively measured against the number of candidates that are rejected. If a recruiter is pulling in a large number of people that all get rejected, that's not due diligence, it's wasting everyone's time and is a signal that the recruiter is not very good at identifying suitable candidates.