My Synology NAS uses something like this for its navigation and even if it's initially strange, you instantly miss it when you access it from your phone, when the UI turns into this nested list which is not intuitive at all
This is definitely a taste thing
It was called MDI: <https://en.wikipedia.org/w/index.php?title=Multiple-document...>
Without their desktop thing, this would just be "open link in new tab" for the apps you want open at the same time.
Spatial file navigation & manipulation might be the one reasonable reason for the fake desktop.