Many programs do not respond to anyone. There is no benefit and only disappointed feelings. Say I typically go down 38 spots to fill my program of 8. If I send “love” letters/responses to my top 20 people, odds are that all of them stand a great chance of matching with me. You would think it would be a safe email. All are usually ranked to match. Now say I pull a great intern class the year before and they sell my “amazing” program for me. Hypothetically, I fill my 8 spots in only 10 people. It doesn’t mean that I didn’t think #11 was excellent. I would have been more than happy with applicant #11. In fact, 10-15 were all great applicants with virtually the same scores and LOR’s and interviews. Responding to my top 20 positively just results in upsetting 10-20 that I was dishonest. Those 10-20 may have a bad taste in their mouth and not apply for my fellowships.
Programs can get 800 applicants for 8 spots. Getting one of the 80 interviews puts you in the top 10%. That’s a fantastic accomplishment already. Out of 80 people, it typically takes less than 40 and in rare circumstances, 10 people to fill. Just because you didn’t end up being liked in the top 1% of people at one program, doesn’t mean you didn’t do a fantastic job in the match or that they didn’t think the world of you.