Small laptop computers are ergonomically useful to children who literally have a smaller body frame. I don't think there were many of those around prior to OLPC and/or netbooks, beyond specialty products like the Toshiba Libretto and perhaps the original Psion Netbook. Nowadays we still have low-end smaller ultrabooks that are effectively quite comparable to the former netbooks.
And I don't think there's much available today. I used to have a small Asus for travel (and a small windows Fujitsu before that). But there are very few <13" laptops/Chromebooks available these days.
I believe there were many in Japan - including products like small laptop-shaped electronic dictionaries - but that's Japan. Their homegrown cell phones have recently picked up the moniker "Galapagos phones" because they tended to develop country-specific features and rarely leave to other markets. The same can be said for their micro/portable laptops of the early 2000s.
One could argue that OLPC made people outside of Japan aware that the form factor was possible and even optimal for some users.