Hello!
It works indeed 
I tried the same code before but there was not an mtl file available on the server and it created the mesh with zero vertices, this is why I incorrectly answered here (Import .obj model to scene - #8 by roland). I reexported it from Blender to generate the mtl file and voila! mesh.getVerticesData(BABYLON.Constants.PositionKind) now returns the positions correctly. I think the SceneLoader should load the geometry alone from the obj file even if the mtl file is not available.