It all seems a bit polarising to have only 2 camps. Plotter doesn't really fit in most cases, because it implies a lack of flexibility, whereas planner has the potential to sound less rigid. Pantser sounds a bit rude and juvenile. I don't like to be labelled with either of these constraints.
I plan, rather than plot. Sometimes those plans are more like a mud-map, a few simple lines in the dirt that give me some direction or purpose, and sometimes, it's a whole itinerary. Sometimes, the map is worth printing in colour. A plan makes it easier to complete the journey, and therein lies the benefit.
Would you travel to another country without some form of planning?
Some would, and I applaud them, but is it courage or stupidity? That will depend on the country visited, won't it? therefore, knowing the destination is important, and if some prep is done ... oh, is that a potential plan?
Whether the parts of the process are in-head, on-paper, white-board, story-board, sticky-notes, coasters (pub-type), toilet-paper (etc.), these are all forms of pre-planning or nesting an idea from concept to premise to story.
Neither plotting nor pantsing is the whole story, and if Stephen King can do it ... (yes, he does. He puts ideas in his head, jots a few notes, and thinks on it, sometimes for years (if you don't believe me, it's mentioned on a TED talk with other authors - the dome idea is one example)).
Therefore, in the end, we all plan to some level, whether we accept it or not, whether we label it or not.