At first I didn't really get your point, but then that's just another sign of old age I guess. Looking back this is what I associate with the word "Laptop": Toshiba T3100/20
Or perhaps this: Ericsson Portable PC
I've worked with both (though I try to forget as much as possible about the Ericsson POS), and at that time there were no 2Â½" HDD's on the market. Even 3Â½" HDD's was still a novelty, seldom found in anything but portable computers. Both these machines were at the time dubbed as "Laptops" as it was possible to balance them on your lap, in theory at least. I think I tried that once with the Toshiba, and never felt compelled to try it again.
As I remember it the "Notebook" moniker was introduced when portables weighing less than 3kg started to appear. By that time the 2Â½" HDD's were widely available, and almost exclusively used in these "Notebook" class computers.
So going by those definitions you could most definitely have a "Laptop" with a couple of 3Â½" drives. I seem to remember something about a monstrous high performance dual Opteron "laptop" with two 3Â½" drive bays and RAID-1 & 0 support. It had it's 15 seconds of fame about a year ago. However I've never seen it IRL, nor heard from anyone who has touched it. Not even a friend of a friend whose dog once sniffed in the footprint of some one who has seen it, so it might have been a mirage...
(sorry for going of topic)