No, it is not an oxymoron.
Mass customization is a social behavior of the modern consumers.
In fact, sociological studies show that modern consumers select to buy personalized and unique products. Everyone wants to be integrated and accepted in society, in the end. How can you do to be accepted by society, but remaining anyway yourself? You can buy a trendy object, and then you can personalized it!
The phenomenon of mass customization can open a lot of opportunities for manufacturing industry! The ultimate objective should be the single order, manageable with cost and time fitting to mass production.