I've seen a metric fuckton of fang (gvh) art all over /v/ yet none of it evver seems to get posted here. Is there some sort of restriction on her or is some 'avoid posting' hotpocketeering keeping it away?

As long as the artist isn't on the avoid posting list (and ideally you'd get permission from the original artist if possible), then feel free to post the art. Sometimes things just slip through the cracks.

47 posts is pretty good for an unproven narrative-game that isn't even out. (by the way you can link to searches by enclosing a tag in double braces {{fang_(gvh)}} or wiki pages with double brackets [[fang_(gvh)]]. I'm just gonna put fang_(gvh) here because honestly I didn't even recognise the abbreviation.)
There's no conspiracy here, it just hasn't caught on. Individual characters never get DNP, and the registered rightsholders themselves would have to get in touch with the site to set up any posting restrictions for trademarked content, which will be clearly noted in the wikis.

If you're good at sources and tagging you're welcome to post some yourself, but be careful about posting stuff straight from a place like /v/. A good rule is that unless you know the image you're grabbing was directly posted by the artist, it's not a good idea to post it here. Sometimes drawthreads are good (if the art is up to quality standards), but it will be a little harder to get anonymous_artist posts through, and if possible try to find out if the artist posts elsewhere.