I agree.
I already created a Feature request a few days ago before reporting this case. It includes a use case.
See here:
Add tag of objects in outliner, allow sorting also by component name and tag - SketchUp / Feature Requests - SketchUp Community
In general, I do not modify 3DW components, if they are not too heavy in size. Like this I do not have to keep a local 3DW repository copy.
The complete project I have is a model of a house with all details (furniture, plants, garden, windows, doors, solar panels, technical installations, etc.) and it is only 37MB large. It is all good, except the outliner performance issue.
I like the idea of preventing a drill down into locked objects. I would even say, that the existing “lock” flag should be used for this. If the drill down shall only be prevented for “expand all” or in general, I leave up to the SketchUp team.
A use case for this is the “import a visual reference model from Trimble connect”. See the menu option" File->Trimble connect → Import visual reference model".
If you import a model as a reference, then this model is a locked object and is added as well to the outliner. When I import the surroundings (including trees, plants, streets, neighboring houses) into my model as a reference, I expected to get one entry in outliner where I cannot drill down. But instead I get the full object hierarchy of the reference model in my outliner making it unusable.
I will add this to the Feature request.