I always thought it was a combination of people wanting or needing new computer and an economy that meant they couldn't afford normal notebooks that led those who would normally purchase notebooks to the netbook world for a few years. There were a few people out there who purchased the little machines simply because they were tiny and they wanted portability. The netbook also made a nice first computer for younger users.
You could still find few netbooks in 2012, especially earlier in the year but they were nowhere near as popular as they had been in years past. If you're a fan of the netbook, the little machines are going extinct in 2013. The Guardian reports that Asus announced yesterday that it would not make any more of its Eee netbooks in 2013. During 2012, only Asus and Acer were making netbooks.
Acer also won't make any more netbooks for 2013. Undoubtedly, there will be a few netbook sales this year as retailers both online and in the real world cut prices to clear remaining inventories. Once the machines Asus and Acer have are constructed are sold, there will be no more. The demise of netbooks is blamed on several factors.
Those factors included an uptick in the economy leading people back to more expensive and more powerful machines such as ultrabooks and traditional laptops. The incredible popularity of tablets such as the iPad and Android offerings are probably the biggest nail in the coffin of the netbook. In 2010 and 2011 netbook sales steadily declined from a high of over 2 million units in Q1 of 2010 to only about 750,000 units sold in Q4 2011.