Well, have you?
On a whim just now, I decided to experiment with ye olde Graphic symbol (you know, the ones with those start and looping properties and no instance name). It turns out that once your movie’s compiled, all your Graphic symbols actually dissolve into their parent timeline. So if a Graphic is a child of a MovieClip, then the animation defined by the Graphic will be incorporated into the timeline of the MovieClip.
It’s as if the Graphic never existed; it seems like it’s a fake object with no Actionscript equivalent, used only to make animators’ jobs easier. That explains why it can’t have an instance name, or filters, or a blend mode, yet it can still be rotated, scaled, skewed, and have a color transformation. This also suggests that multiple instances of a single Graphic symbol are dissolved into separate sets of the same animation data; inefficient from a developer’s standpoint, perhaps, but not a big deal to animators.