Users should have a maximum amount of choice in selecting the applications they wish to run. Code sharing and modularity are a good thing. When possible, a common implementation not dependent on a specific desktop increases stability, increases interoperability, reduces system footprint, and optimizes the use of free software development resources. Concept sharing is a good thing. Users do not benefit from the existence of multiple desktops if those desktops do not share their good ideas and work together toward common goals.
Work is the only currency that matters in the free software world.
XDG is an organization made up of developers, designed to help developers do development. XDG does not intend to provide user resources. XDG should be judged by how well it serves the interests of X desktop users.