I see, it seems my explanation was way too simple.
So... Right now in Windows mode this is what I see when I click on Video -> Movies
You can see there are movies that are multiple series, such as 300, Aliens, Animusic, Back to the Future and Blade Runner. There are a lot of movies in same series (or say, collection).
Plex and Jellyfin combine these series into one clickable title.
The view is much more compressed and clustered, much easier to navigate. When I click "Batman Collection" for instance, the screen changes and show me the movies that have tag "Batman Collection."
I see there is "Grouping" tag for the video. I tried to utilize it by putting some movies with same Grouping names and tried to see the list via "Group By" option, then this happens.
I have to say this is not that ideal.
Also, I think this collection mechanics can be used for CD albums as well, which can be definitely helpful for navigation.