I think I see the confusion, rogue waves, by definition, are just waves much larger (twice as large, again from the definition) than the surrounding ones, sufficiently so that they're impossible under the old wave models. So you can obviously get them in any conditions. But you're not likely to get one that can sink a large container ship in otherwise calm seas (although it's not in theory impossible), which is what I was talking about if you go back to my original comment. The height is still proportional to the other waves.
