I thought the same, but it turns out I have quite a number of friends (especially younger, who are sharing apartments with flatmates etc.) who don't have a TV or tablet, and who will just sit on their bed or couch with a laptop for netflix and such. This is totally anecdotal of course, but I do feel like it might be the device stats are quite different from what we might expect.
They are, but only in that you would be surprised at how tiny the PC usage is to most online video streamers, it's even smaller than anyone would expect.