I think most people hate the idea that all regrets are pointless.
People don’t want regrets to be pointless. They want to be able to pin down the mistake or the flaw, or the deciding factor. This damn thing which screwed someone’s entire life or part of it.
If they agreed that all regrets are pointless (which they are — unfortunately for those people) they would lose this possibility. Life would become even more unbearable, I guess.
With regrets they can at least point a finger and say If only I hadn’t gone there that evening, or If only I…