Well, obviously, it’s because if you want to edit one and have the changes reflected in them all (say you made a drum clip, and then decided you needed a different rhythm but had already copied them all across your track), you can do that.
Can you imagine changing your mind, and editing every single one, along with volume and panning, to reflect the exact same changes? Or just editing one, and having all the phantoms do it at the same time, not needing to be edited?
If you never, and I mean NEVER EVER edit afterwards, then you won’t need such a feature, but there’s still no difference. But if you edit after, I’d be willing to bet you will eventually run into the need for this (if not a while later, then rather soon).
edit:
Wait, I’m going to assume you mean like a clip or whatever you call it, right? Not an ENTIRE sequence, surely?