Yes, and No 😉
A component instance is really just a pointer to a dataset describing the component. If you copy/paste a component or pattern it, you really are only creating pointers to the same original data set.
In Fusion 360 that dataset might contain construction geometry, sketches, joint origins etc. which can be found in the browser, but it also contains all the features in the timeline that create this geometry. Extrusions, revolves, lofts etc.
So for a copy/pasted or patterned component, creating an instance is pretty straight forward!
However, when you mirror a component, it gets a lot more complicated, because you cannot reference the same dataset. The geometry obviously needs to be different. However, the geometry originally was created from sketches and features, so what now?
Do you also mirror all the sketches, construction geometry and and features ?
How do you keep them "linked" to the original features, because if you don't it's not an instance but an independent copy, which you don't want?
There is a lot more data needed to do that and then that also creates the need for more data management, which in return requires more computational resources.
Can all of that be done ? Sure, but it's questionable whether the benefits outweigh the efforts 😉