Why the clear-surface rule exists at all
Paper on a desk in a professional office is somebody's live work. It may be a draft in a particular order, a signed original, a client file that has to stay in a controlled place, or a note that means nothing to anyone else. A cleaner who tidies it has changed the state of that work without being able to judge what mattered. The safest position, and the one most practices actually want, is to leave it exactly as it sits.
The mirror image is just as important. If the rule is unwritten, some cleaners will move things and some will not, and the office notices the inconsistency long before it notices the dust. Writing clear-surface-only into the scope means the desk gets the same treatment every visit. Staff who want a full wipe learn quickly that clearing their own desk before they leave produces it.
