Doubtful. Its no harder to stack them today than it was years ago.
Well, Hitachi just announced the first standard thickness (9.5mm) 2.5" laptop drive to have 3 platters! Normally that has to be at 12.5mm thickness.
It is the Hitachi Travelstar 5K1500. I'm sure it'll have lousy access times. I'll never buy anything other than a hybrid drive or SSD