Everyone goes to the holodeck to fuck, and apparently they make the lower deckers clean out the biofilters?
Why?? Just dematerialize it on the spot and send it back to the sterilized organic particulate suspension tanks! (TNG Technical Manual p. 91, the tech manuals are cannon deal with it nerds 😎)
Whatever the technical reasons or not (and I treasure my original printing copy of the TNG Technical Manual too), my take in the Lower Decks tasking is that it falls in the toothbrush-to-clean-grout category of character-building tasks for junior officers.
Isn’t a starship computer technically advanced enough to automate most tasks? And we never see the cleaning bots but they’re implied to exist.
In a post scarcity luxury world you don’t really need jobs, but I think they understand that people should still do them because “it builds character.”