True Instance Object is now possible
Blender has data link, but no true instancing, where the source is used as an object&mesh source and the instances are only editable on the object properties. Now, this method exist in all other tools, in CAD its named blocks and the advantage is performance. However the need of true instance was very underestimated in Blender. But with geo nodes it becomes obvious how important instances can be to performance, and with instance hierarchy option it would even make collection instance obsolete. The main different lies in the usage if modifiers. Ao currently every data link becomes realized geometry when ever a modifier is added. First of all that happens on subdivisions. So in other words objects with subdivisions are never instances, which lead to performance problems. The work around with geometry is simple, just take any base mesh, add the geo node modifier and use a reference object as output.. simple, ans so simple could a instance object work, that does that automatically. That way you could also add a hierarchy if objects and maybe lights in the future.
3 Comments
One can't have both - perfect memory savings and full editing flexibility.
In order to do anything with the instance data, it needs to be handled and copied, even if only temporarily. Any program that works with instances must do this.
It's just that what you may see in the old modifier stack is made explicit in the geometry nodes through the realize instances node. :)
If you can, try to adapt your workflow more in that direction. It has a steep learning curve at first, but it really pays off.
Try this: Geometry Nodes editor > instances > Realize instances
Documentation
Yes it does.