Stephen Bain wrote:
NPOV involves determining whether viewpoints are widely held, are held by substantial or significant minorities, or are held by an extremely small or vastly limited minority and therefore not suitable to be covered in articles. This is an editorial decision-making process that all editors perform all the time. Determining which filters to work on is entirely analogous to this process, which is inherently neutral.
Gauging a viewpoint's level of coverage by reliable sources is achievable via objective criteria. We don't take anyone's side and aren't bound by practical limitations on the number of widely covered views we can document (irrespective of the quantity of articles required).
Conversely, category-based filtering would require us to accept/reject our readers' views in a binary fashion. (A type of "objectionable" image would either receive a filter or not.) This would convey a formal determination that x beliefs warrant accommodation and y beliefs don't, which isn't remotely the same as documenting these views in a neutral manner.
Perhaps you have in mind that we could accommodate objections that are "widely held" or "held by substantial or significant minorities," thereby excluding only the ones "held by an extremely small or vastly limited minority." As I noted in another reply, setting aside any philosophical issues, this isn't technically feasible. For logistical reasons, the numerical limit would be far lower (with an example of "5–10 categories" cited by the WMF).
The above doesn't even touch on the categories' population, which would entail non-stop argumentation over whether particular images belong in particular categories. Once again, contrary to the creation of articles documenting a wide range of views, the decision would be binary: filter or don't filter. Unlike our normal categorization scheme's large number of objective classifications, this would rely on a small number of subjective ones (created not to provide neutral descriptions, but to label the images' subjects "potentially objectionable").
There's no need for any of this. We can accommodate _everyone_ via a vastly simpler, fully neutral setup. If you haven't already, please see the relevant discussion: http://meta.wikimedia.org/wiki/Talk:Image_filter_referendum/en/Categories#ge... or http://goo.gl/t6ly5
David Levy