As an ex-controller, perhaps I can offer a slightly different viewpoint. As has been suggested, many VRPs around an airfield are designed to permit easy routing toward downwind or base leg - and thereby keeping VFR traffic away from approach and climb-out paths.
Although it's a good few years since I was operational, I suspect things have not changed greatly but if an aircraft had difficulty finding a VRP, rather than vectoring it I would usually identify it and then monitor its progress toward the field and until it had the field in sight - that is, allowing the pilot to navigate visually which is what was typically going on when flying VFR. The field I worked at had terrain and built up areas pretty much all around it and vectoring a particular aircraft would usually create as many problems as it solved and I tended to do so only if the pilot was having difficulty navigating (rather than simply having trouble finding a VRP).
On another point, using positions or locations that were not notified in some way was normally limited to locally based aircraft with voices that I recognised (usually instructors) and who I could have confidence would know where I was talking about. Maybe it was easier for me than some others because I sometimes flew from the based flying clubs sometimes. If the pilot wasn't familiar with a particular place it was no problem, there was always a plan B that could be used.
Final thought - in my experience VRPs were always selected with half a mind on how easy they were to find and, ideally, based on a big and easily identifiable ground feature. Once again, I doubt that this has changed much in the last few years.