ok thats the best description of the idea i could come up with but give me a chance to explain.
i’ve be thinking alot lately about material libraries, mesh libraries, node libraries etc.
now there are some addons out there that try to solve the issues but never completely successful (IMO).
the problem i find is the lack of visual reference when linking a group or other data from a .blend file.
If you could load two .blends at once, like some other apps do, eg Final cut pros multiple projects. you could have your main scene open and then open your Materials.blend and drag your required material into your current scene.
you could have a library of nurnies/greebles and open that and drag them into your main scene as required. trying to load a model from another .blend by looking at a list of names is not very intuitive, it’s ok for an existing object i.e “ford car” but for fictional objects it is often hard to name such objects so they can be easily remembered.
basically if you have the screen divided in two the left is your main working scene and the right is a library .blend you have opened.
I do this already by running 2 copies of blender and opening the library blend in one window letting me view the objects/materials and check their names before linking into my current .blend in the other window but its not a very comfortable way of working.