True, my 7cm Kent Wang tie is not that noticeably different to my 8cm HC tie - except that it narrows substantially earlier. So it is much narrower at the point where the blade of the tie goes into the knot. Thus it doesn't dimple very well.
To achieve a good dimple, I think that having a tie that stays fairly wide right until the knotting point is crucial. Otherwise there simply isn't enough material to make the dimple "W" shape.