I see your point, I’m aware of the Object and the object-data difference, with “packing” I exactly meant creating “hidden objects”, not visible in the outliner, with object container and data to be instanced, of course this process happens behind the scenes, transparently to the user. Anyway, I’m totally ignorant on blender internal software architecture, so I don’t know if it even makes sense to talk about how to implement something like that internally.
It would still be great if it could be possible to have a workflow that doesn’t necessary relies on external objects, like the one described by @dfelinto in this post (on-the fly creation, opposed to the asset workflow):
It would be even greater if instancing objects created directly in the tree, wouldn’t generate a performance loss due to raw mesh data copying and not instancing.
In houdini you can just create objects primitives, edit them with nodes and then copy instances to points, It would be handy to have the same workflow possible. To be honest, I don’t know if Houdini instances geometry or just copies it, losing performance as well.