The last time I was a hiring manager, I committed to giving feedback to anyone I rejected after the very first screening step. This was about 25-30% of applicants, which (even for a role in considerably less demand than engineering jobs) ended up being many dozens of emails. It was a giant pain in the ass - and it's pretty emotionally draining because you're turning down people who would really, really benefit from getting hired. I did it anyway, because I'd promised to, but it was not fun.