The problem is that the guidelines state that caches should be at least 528' feet away from each other (generally speaking) to prevent confusion AND to prevent saturation of an area.
I never just drop a cache in the field. If I see a place worthy of a cache, I don't mind grabbing coordinates, doing my research, and returning later to place a container. If you place a cache while you're out in the field, then yes, you run the risk of being too close to another cache or stage and you might need to go back out.
You are taking statistics out of context. Of course there are more caches hidden too close to traditional hides because they are more prevalent. Not everyone has the equipment to track or remember where all the hides are. Even if you do, you can't know where the puzzles are hidden. If you are not good at or for that matter like puzzles you are pretty much screwed.
I will repeat, who cares if a puzzle gets accidentally found? You can't log a find if you don't know the name or GC#. Who get hurt if the unknown puzzle cache, I repeat, unknown puzzle cache gets found. IT IS UNKNOWN FROM WHO KNOWS WHERE OR WHO KNOWS WHO.