Personally, I hate this too. I once spent over 20 hours interviewing and testing with a popular personal financial tool. Out of over 500 applicants I was one of the final 3. Even that wasn't enough to merit anything beyond a templatized rejection letter, and radio silence when I asked for any information.
Professionally, I still hate it, but to some degree I understand it. Forgetting even the matter of additional business spent personalizing rejections, the truth is that most of the time the rejection will be taken personally, feelings will be hurt, and any feedback given won't be actionable anyway.
"Sorry, you look good on paper, but your solution to the challenge you was buggy, and you misunderstood the requirements. Go become a better developer."
"Sorry, your code was good, but you struggled to convey information to us. It appears you're a terrible communicator and that would cause problems on our team. Maybe some books on the topic would help, but I doubt it."
"Sorry, you aren't a good fit for our culture. You're abrasive and rude, and talked to the interviewer like you knew better than them. Quit being a narcissistic jerk."
If you're talking about being rejected at the application stage, IME it probably means you didn't follow the instructions completely, you don't actually meet the requirements (remember, it's probably HR or someone non-technical doing the first stage of rejections; they're just driving by checklist, so simple things sometimes get triggered here; if the requirements say "5 years JavaScript experience" and you list "5 years React experience" that might not make it through their filter), or your resume/application needs revising.
Your examples presume that the interviewer actually has actionable feedback for you.
Many people who interview candidates have no clue what they're doing. I also started out winging it. And I don't see much training being given to new interviewers, apart from being interviewees.
The chief mistake is interviewers not giving feedback on the spot to check their assumptions/conclusions. Following procedure, but not actually collaborating with the candidate on their shared objective; finding out whether there's a good fit.
On both sides of the table, my advice would be to ensure that the conclusions you're reaching are openly and explicitly put on the table for discussion right there and then.
Professionally, I still hate it, but to some degree I understand it. Forgetting even the matter of additional business spent personalizing rejections, the truth is that most of the time the rejection will be taken personally, feelings will be hurt, and any feedback given won't be actionable anyway.
"Sorry, you look good on paper, but your solution to the challenge you was buggy, and you misunderstood the requirements. Go become a better developer."
"Sorry, your code was good, but you struggled to convey information to us. It appears you're a terrible communicator and that would cause problems on our team. Maybe some books on the topic would help, but I doubt it."
"Sorry, you aren't a good fit for our culture. You're abrasive and rude, and talked to the interviewer like you knew better than them. Quit being a narcissistic jerk."
If you're talking about being rejected at the application stage, IME it probably means you didn't follow the instructions completely, you don't actually meet the requirements (remember, it's probably HR or someone non-technical doing the first stage of rejections; they're just driving by checklist, so simple things sometimes get triggered here; if the requirements say "5 years JavaScript experience" and you list "5 years React experience" that might not make it through their filter), or your resume/application needs revising.