Blend shapes and batching

I saw a GDC video a while back where the creators of Abzu talked about how they used blend shape animations to facilitate better batching of animated low-poly animals. How does this work, and does it apply to Unity? The amount of skinned meshes is usually quoted as a performance bottleneck in games, but i noticed that blend shapes in Unity are tied to the skinned mesh renderer. Are there any performance benefits to be had from using simple blend shape animations?

Link to the video:

 

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