I don't think that a modern hiring manager can afford to think this way, especially when tech wages are so high.
The author (1) took an action in a specific situation, and (2) generalized that action out to a broader rule covering hiring in general.
The author's actions in (1) were absolutely correct (especially after giving the applicants a three week course!). The author's generalization (2) is just wrong.
#2 is more discretionary. Letting someone exactly why you chose not to hire them is a nice thing to do, since it helps them sharpen their prospects for the next gig they go after. But the bottom line of what they're looking for from you is (as you state) a "yes" or "no," not a comprehensive review of their life choices to date.
#3 is even more discretionary, to the point where (to be blunt) I find it completely baffling. Interviewing a job applicant is entering into a very specific business transaction with them -- they agree to present their qualifications and answer your questions, you agree to review them and decide if they meet the needs of the open position. They're not entitled to anything beyond that from you, and I doubt any reasonable person would expect anything beyond that from you. At this point you're just creating work for yourself.
A decent candidate will learn from difficult questions and things they tripped up on. If you are acting professionally, asking pertinent questions and responding to the candidates answers then you are providing all the help they should need to nail their next opportunity.
Of course you can seem to nail the interview and get no-where but in that case you're being rejected for something out of your control (another better candidate, internal politics) in which case you have a good chance at your next interview. Or you are delusional about your own skills and experience, not sure what to do there though!
Will you be satisfied that you never got any feedback to why it was refused, what you did wrong and what to do to fix it?
Feedback, be it good or bad is crucial. I, myself appreciate this feedback, especially in this scenario the author is talking about. How am I supposed to improve my self when I don't even know what I am doing wrong?
People who have just rejected you will never be reliable sources for feedback (on average). That's what friends, confidants, and inside sources are for.
If you help those candidate by referring them to a job at another company then both the candidates and the other company will love you.
Months or years down the track, when you need to hire more, you will have a list of good candidates, and companies that may refer candidates back to you.
Life's tough all over, you know?
I mean, if you know of an opening they would be good for off the top of your head, sure, go ahead and refer them. But you're not obligated to go find them that opening.
However if I ran a company I would have an eye on both the short term and the long term. It is good for the long term interests of the company to be loved (by customers, employees and the community).
Doing very cool things for people, especially when it takes little effort or money, is a great investment to create goodwill in the future.
Being good to people is just so easy, but so many people hide behind "business transactions" as if that's a reason to turn their back on somebody. Be a fuckin' person, would you, guys?
I have a feeling this worked out for all parties because who knows how they would have chosen hires otherwise? In this way, as the article states, they got literally the cream of the crop as basically elected by the crop. That's pretty sweet. And in return, for the crops contributions, they got some free advertisement for their work by being a part of the groups, learning new languages, solutions, and theories.
Had their interview process been less intense then I believe a clean no would certainly have been appropriate.
My one buddy, this is anecdotal of course, has a biology (or some sort of major like that) B.S. and can't get a job at all. I remember him telling me one time that after sending out so many questionnaires and e-mails and making so many phone calls that very often people wouldn't even reply. He told me that one time he got a response that said "We're sorry but we're considering other people" and he actually responded "Thank you so much for the closure."
In that case, it might seem that you owe people at least the clean no!
Everything works smoother in lots of different parts of life if all parties understand the concept of a Clean No. Not "You can say No but then you still owe me such and such". Just "No." Anything beyond that is a gift.