Loads of mobile games use 2D models and meshes to speed up development time. They allow animation without having to draw frame by frame, and still have elaborate animation. The same as in 3D. Rendering to frame by frame makes a tradeoff between choppier animations or exploding the space required. Spine 2D is an example of a product where these animations can be made in full.

Unity is big in the mobile market, which in turn has more addons and plugins to support these workflows. Godot can support it without rendering the animation to frame-by-frame, but it doesn't have a universally known plugin yet. Most artists don't look forward to doing the exact same thing in Godot with worse tooling.

That’s really interesting - thanks for taking the time to come back to this.

When I first clicked over to Spine 2D I assumed it was skeletons for sprites. But it actually looks like skeletons for 3D meshes, which are then exported for use in 2D applications.

This sort of workflow implies to me - a layman - that the 3D modelling part is less onerous than creating a whole bunch of sprite art. Which is surprising.