I also prefer that backgrounds be both 1) art and 2) complete to be considered a proper background.
I've seen people upload "audience" characters that are just surrounded by white space or the like, and that may be a small step to creating a decent audience background, but most people who make requests aren't asking for a resource that they will have to do work on to get the final result (typically due to a lack of familiarity with how to do the work).
Example: found a file with a couch and girls on/behind it, but there was no room/setting/actual background to speak of. I tried photoshopping this object into an actual background of a room, but I'm not the best at that sort of thing and I hesitate to upload something that combines other people's "work" without their consent/credit.