I see there are “workarounds” for this, but seriously, let us make collections that include items from multiple libraries. I want to be able to create a collection for “Marvel Cinematic Universe” and include both Iron Man and Daredevil, “Star Wars” that includes The Last Jedi and The Clone Wars, collect Jack Ryan with Clear and Present Danger.
If you create a collection with the same name in a Movie and TV Show library, Plex will display them as related items. If you’re i.e. opening your Star Wars movies collection, Plex will also show a section “TV Shows in Star Wars collection” (same for “Music in Star Wars collection” if you have a collection with let’s say Star Wars soundtracks).
I suspect that’s what you refer to as “workaround”… just wanted to point it out as I don’t consider it a mere workaround. Personally I don’t want my collections to merge all related content without giving some kind of structure