There was a whole push for netbooks like the Asus EEE PC that happened around the same time as the original XO.

Yep, I had both an XO and an EEE in that order. The look on the university help desk tech's face when I brought the XO (running puppy Linux at the time) in to get a network cert install was fun. I recall moving from the XO to the EEE mainly because the latter was faster and more pleasant to type on. There were few other competing net books at the time.

Then "direct descendants" is just a poor choice of words for describing an entirely different relationship.

If nothing else, I would say that chromebooks are a spiritual descendant of the OLPC. Inexpensive laptops with simple software marketed heavily towards education.