It’s not. It just has undiscoverable ui and is unrepresented in the viewport.
My headache is where to put the original collection and/or hide it from rendering while not hiding the 400 instances of it from rendering. My solution was typically to just put original collection below the floor grid, which is why I put so much effort into finding out that I could change the origin point used by instances: Is there anything else you should know about collection instances? - Tutorials, Tips and Tricks - Blender Artists Community
Select all the arm objects, and add them to a new collection, call it “Arm”
I have 13 objects that make Arm Type A.
I have 5 objects PLUS the 7 of the 13 objects from Arm Type A that are used to make Arm Type B.
I want all robots in the background to not use subdiv modifier. I want 2 robots in the foreground to use subdiv modifier. I don’t see how that’s going to work.
Now if Arm Type A is a group and Arm Type B is a group (not sharing any of the objects from Arm Type A). Then I could see a subdiv modifier applied to the Group Instances used in the foreground robots…
I’m not sure my example above makes complete sense. It might be totally off… but that’s the complications of trying to reuse collections when I think of giving it a group sub mode and a non group mode. Actually part of my problem in the stuff I wrote above could be partially solved by allowing subdiv modifiers to be added directly to collection/group instances… which is sort of something I’ve been doing with geometry nodes already.
This would make collection to appear as a physical object (empty) in the viewport, which would allow us to set the transform of the collection.
Surprisingly, Maya users prefer to not have to see and empty for each group all of the time. It seems to be a real pain point of using Blender for them even though, as far as I can remember, “ctrl+g groups” in Maya were just parenting the objects to an invisible empty, same as in Blender.
I still highly doubt 90% of daily blender users even know about the “objects in multiple collections” feature. If I’m right, collections should have never been created in the first place and they should have just made regular old “groups”. … I just checked and in 2.79 you could “Link object to Group”, again reinforcing my belief that “Collections” today are just the same thing as the horribly mislabeled “Groups” from 2.79.
A lot of Maya users would be happy if ctrl+g just parented to empty by default and the move/select tool had modes where clicking a child object automatically selected its direct parent or oldest ancestor or all siblings or all siblings and first cousins. They would also want the ability to hide the parent empty object or at least have more options for what empties could look like.
As in, any instance, anywhere, can be edited in place as if it’s the original collection? There are already add-ons that do this quite successfully it seems. But like i said, collections seem to have not been touched since 2.80 and it fries my brain that they don’t see the benefit of adding this natively. In 2.79, Collections (wrongly called Groups) only existed in the bowels of the Blender File. Perhaps the same should happen with a collection when converted to an in-place instance?
and if I was able to offset/transform the pivot of the collection instance
You can.
coming from Maya, I can tell that I missed a collection system to organize the scene without affecting the hierarchy.
I have one outliner set to only show collections (Maya Display Layers) and another set to not show collections at all (Maya Outliner). Hierarchy in one. Organization in the other.
Maybe an alternative solution would be special collections, simply called “Groups”
The “special” is an object being in multiple collections. While it has been really useful for me a handful of times… if hardly anyone really uses it very often… I’m all in favor of just removing that ability entirely and turning Collections into Groups. Change the name, add ctrl+g default hotkey, implement UI around showing/changing the group origin. Job’s finished.
Nice to have: Close/Lock a group to turn it into an instance in-place. Edit any group instance in-place as if it was the original.
Later we can add back in “collections” as a way to categorize objects with all the flexibility of “hashtags” as in a single social media post can have infinite “hashtags” also known as a single object can be in infinite collections.
Calling it groups will not confuse people because of the old Blender naming conventions, which as far as I know was just parenting.
Download 2.79 and try it. Select 2 objects. Ctrl+G. ??? NOTHING HAPPENS that you can see. It created a “group” elsewhere in the “blender file”. Shift + a > Group Instance You can add an instance of the group you created.
Make 10 objects. Randomly assign 2 objects at a time to 100 groups. Yes you can have 1 object in infinite groups simultaneously. “groups” in 2.79 are literally Collections but without the render visibility toggles.
Then to say: “we can do better” is a strange mindset in my opinion
perfect is the enemy of good
hidden objects than visible. Turning the Exclude From View Layer checkbox off and on resets every eyeball. It is the single most infuriating thing to me in Blender. It does this for sub-collections as well! 
