Everything I've found seems to indicate that in order to export a vertex animation a point cache file must also be generated, but that means in addition to the FBX file a whole new folder with that cache data must also be built. Is there no way to store the (vertex) animation data entirely in the FBX file?
That's correct. The FBX stores the mesh/topology, and the point cache stores the offsets of the vertices over time.
The FBX file format stores mesh topology, shapes and skin deformers, but not the actual vertex cache data since it can be of various formats, such as MCX (Maya), PC2 (Max) or ABC (Alembic). Also, for access and performance reasons, it is preferable that the cache data stays in a separate file so that software can read asynchronously from it without having to deal with the complexity of the FBX data model.
来源：https://stackoverflow.com/questions/9382352/vertex-animation-stored-in-fbx-file-without-using-point-cache