what killed netbooks was very simple: subpar build quality, and stagnation.
Netbooks never got better, even when the Atoms got slightly faster or added x64, they were still capped at 2GB RAM until the very end with some AMD netbooks existing.
Also the build quality of consumer laptops of the time was terrible. It's easy to forget how awful consumer laptops were for years compared to the HP Compaq/Elitebook, Dell Latitude, and Lenovo Thinkpads of the time. They were made with cheap plastics, with keyboards that flexed and typed poorly.
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