They don't have to go through the list to figure out who they're saying "no" to, they go through the list to figure out who they say "yes" to.

They don't provide reasons, because there probably isn't a specific reason, other than the application wasn't one that wanted to make them say yes.

Feedback wouldn't necessarily be very useful. The feedback might be a meaningless number such as '42' in the Hitch Hikers Guide to the Galaxy Deep Thought (which doesn't really explain the result of the question).

At which case, I could ignore the feedback.

I don't see any room for argument here: the lack of feedback is a loss of information.