There was a form letter when my child applied that said something to the effect of “we understand your child applied ED and we appreciate this vote of confidence.” No problem with that. My kid was deferred to RD then rejected. No further communication throughout, except for news from the school about the amazing class they had admitted. The funny thing about this is that I was not enthusiastic about this school for my kid, so while I wasn’t delighted about the decision, I was also a bit relieved that it had come off the table. Stats were in-line and we were FP, so perhaps they agreed that it wasn’t a match.
Your question is an interesting one. I suspect that a WL, rather than a rejection (only 1, btw!!) would have felt like less of a slap. I suspect we weren’t big enough donors to have merited the treatment friends at other schools received with their bad news, such as a heads-up and brief explanation to the CC at school.
My kid ended up at a place that was a great fit, so it’s not like this changed our world. But it reminded me that this school had been impersonal when I was there and still was and that I had other institutions I felt a greater affinity for.