Blender is requesting from many years to get the source code of the FBX format but Autodesk refused and did intentionnally the minimum to document it also the licence isn't compatible with Blender because GPL forces to share the source code of the whole software. The result is that many developpers have been discouraged to implement it in Blender and it sometimes breaks. Blender can't use all of his features or export some data of Blender in the FBX. Autodesk can freely add a new export option in the FBX and make it only compatible with a proprietary tool, they recently did it: the Autodesk Stingway shaders and textures can directly be written in the FBX and be read by Unity while Blender can't write his shader.
Also the open source community and developpers can't improve it, they have to adapt Blender to the Autodesk's specifications.
Autodesk has announced that they have given the source code to Unity for the 2017.2, that also means to impose the use of an Autodesk software by speeding the game creation workflow if we use their products. They want to sell more Maya LT for indies game artists.
A petition should be made against this anti-competition collaboration, glTF by Khronos Group needs more attention: https://godotengine.org/article/we-should-all-use-gltf-20-export-3d-assets-game-engines