There might be more reasons the conversation got confusing.
But essentially as I see it, it was simple.
The request originated out of a need to have a package bundling solution to reduce file size for versioning.
If it was mentioned in the original post, I missed it. But there did not seem to be any mention of packaging the data for use outside of the Blender ecosystem.
From that, the conversation went into a few logical directions.
First - why are your files sizes getting out of hand?
Why are you versioning scenes with a lot of local assets and large footprints?
Linking is the system currently the method of building large scenes of libraries with a small footprint for versioning.
The request was for some kind of Blender file format that would also be structured similar to how linking already works.
Why not linking?
Because it has limitations.
But you can’t talk about linking and its limitations without discussing production pipelines and understanding how to use linking within the context of limitations and most importantly without a discussion about pipeline best practices.
USD was first mentioned as a format within an addon that would combine various methods (not linking) and used to transfer data within a Blender ecosystem. As I understood the first post.
But it later spun off into its own topic.
Put simply.
Linking and libraries is the current imperfect but workable solution to the original request.
Also there are other threads that are currently discussing these same topics.