Let’s start by getting right to the point: When someone is rejected from a job they’ve applied to, they deserve to know as soon as possible. If they ask for feedback, it behooves you go give it.
I’ve searched for a job often enough myself, and watched plenty of people do it for years at a time, and it is hard. It’s a hard, hard process and it takes all of your energy just to keep up your morale. And as hard as it is to be on the side of the table that’s trying to hire someone, it’s far harder to be the one who’s looking for a job. After all, your livelihood is at stake.
Coming at it from that perspective, I really don’t understand why companies simply stop talking to candidates rather than rejecting them, and why they refuse to offer feedback when requested. A little empathy is in order. And if not empathy, some appreciation for the possibility that one day you may be on the other side of the table. Wouldn’t you want to know that you were rejected? Wouldn’t you want to know what you did wrong or what skills you need to improve?