It's more aimed towards rendertime operations. Say I want the excitation as a driver of some shading attributes (could be displacement, specular roughness, a blend attribute for different maps, etc...).
I've tried a test export, I connected the zLineOfAction.length to my objShape.user_attr and it works fine. I can import this alembic file back in Maya and the value is changing over time. I guess there could be a workaround to normalize those values, but I thought it would be easier to directly access the normalize data for the zFiber.