RE: '06 Pure Acid 86L tail shape
Well, I'm actually not fully sure what the intentions of the shapers were. As you say, some freesytle baords have this kind of tail, German SURF mag actually explicitly talked abou the PA74 being a good high wind freestyle board, so maybe it does help with that.
Otherwise I just think its a way to add some tail thickness while retaining a sharp release. It must for sure be much easier to make the board stronger with this slighly thicker tail.