Would this cover anything outside of what Graphic Design (GD) already covers? Or is it just trying to be a more specific site than GD?
I am the creator of this proposal.
For me, this question is like saying that Arduino or Raspberry Pi SE shouldn't exist just because you can ask it on SO. We create new sites for asking more specific questions, where any user can answer you. On SO, when you ask a specific question, you have to wait longer before user that knows something about your question comes to answer it. That's why developers got an idea to create more sites about all activities for more users to join SE. So is my proposal.
I think, this proposal may be not only more specific than GD, but also more general. I.e. it may cover some non-graphical aspects of animation production (e.g. direction, sound direction, production etc.).