OK, a "cheery" thought ;)
Imagine someone you know is in a monstrous accident. I'm not sick. You're only imagining, not hoping.
This is not your average car crash , but an enormous splurge of blood and guts, the like of which is only seen in X-rated movies and video games. Perhaps one saving grace, the head and brain are instantly crushed to a pulp, so instant death and no pain.
However, the rest of the body is splattered into a thousand pieces, with bits of flesh and bone and bone marrow all over the place.
Now, if you are the sort of strange person who thinks every potential human life is a life worth saving, then every bit of that bone marrow needs to picked up and cared for separately. Because each individual bit could have individual stem cells that could grow up into completely independent human beings.