> In my view, the lack of singular vision and focus is not something intrinsic to FOSS. When i look like at projects like blender3d, Cpython, linux kernel,LLVM etc...

I think one of the differences here is that the Desktop is more of an aesthetics and ergonomic thing compared to your examples above. It's harder for people to agree on and when there are subjective feelings around it instead of objective, there is a need for a central decision point which takes quick decisions.