This is a BS article. The HR types don’t say “No” (1) in case a candidate they chose does not turn out well and they need a back-up, and (2) in case they are challenged or worse still, sued over a ‘refusal’. And yes, overwork/laziness may be in there as well when you may get 1,000 applicants for a position.
there’s a big difference between dealing with 1000 apps for one job and actually bringing in a far smaller number of people for interviews. The latter group deserves a close-out email and/or phone call. A hospital I worked for wouldn’t contact anyone unless the job was actually filled. So, if they didn’t like anybody, then the ones who interviewed never heard back. Not very professional unless the applicants were told what the drill will be.