That doesn't explain why companies killed netbooks though. A lot of the low-end full sized laptops are now running netbook-class hardware at netbook-level prices, with all the performance issues that goes along with it. You just can't get anything smaller than 15" anymore without either shelling out for an Utrabook or Macbook or buying a Chromebook.
To be fair, OEMs didn't kill netbooks. Microsoft and Intel did - by stopping the OS and processor deals that made netbooks possible in the first place.