It hurts a lot for a candidate to hear that he is not selected, no one likes to hear NO, which is the general human nature. From the facial expressions of HR and by the tone in which the HR says "we will get back to u later". the candidate understands the hidden meaning, i.e he is not selected. But if tomorrow there is no candidate for the HR, he can always call back the candidate whom he told that we will get back to u later, and at this time the candidate if still searching will thank his stars. This situation creates a win win situation for the HR only, and not for the candidate.
You know what, I once gave a telephonic interview, and got a call for personal interview, after 3-4 months, this clearly gave me the idea that they must hav selected someone and he must hav left after 3-4 months so the next candidate i.e I was told that the opening is still open and I can attend the interview.
Here I very diplomatically increased my CTC, and told to attend interview I would need travelling expenses, since then I have not heard from them, probably they must be flabbergasted by my reply.
Best practice is after the finalisation , a letter needs to be sent to rejected candidates mentioning they are not fit for the job, or not found ok.