This is a very important functionality that we need for our interior design firm. We work on large hotel projects within the architect's linked model. If we are working on a design option within the architects linked model, we need to be able to remove certain bits of the architectural work so we can draw our revised layout proposals. This is extremely painful to do under the current circumstances. It is crucial to our work to be able to hide and unhide elements within linked models. This is not possible using the API either...believe me, I've tried:
https://forums.autodesk.com/t5/revit-api-forum/hide-elements-in-linked-file/td-p/5777305
James