That obviously wasn't the part I was responding to. There's more than one point floating around this discussion. No need to take the bad faith approach and assume I'm responding to the blame issue. No need to be rude.
There's no need to shame students. But I'm talking specifically about why schools have policies like this. Often you need to design policies so that blame isn't assigned. Instead of litigating every late homework assignment, you except X number of late homeworks. Or you simply accept none and give opportunities for extra credit.
Teachers often have to design policies so that they don't need to do a bunch of litigation. Instead you have blameless policies and simply have enough buffer that a few negative occurrences that aren't the kid's fault won't affect their grade.