I've wondered the same. I assume it is a sort of "do no harm" approach. "I'll explode your notes for you, and I'll put them over here is their own container so they don't interfere with your outline too much."
I could see a case where I have several notes in an outline, explode the second one of, say, twenty, and then have to stop and consider which ones are the new ones. Especially if that container has a sort rule, then the newly added notes might get flung to all corners of that container.
Also, if I get the Explode parameters wrong or I'm not paying attention, then having the result in a container makes it easy to blow away the bad results and try over.