Here is another reason why:
Google Chrome version 50 was released to the browser’s stable channel yesterday, and in addition to a handful of new features and security fixes, the update also ends support for a wide range of operating systems that have been supported since Chrome launched on those platforms. Windows XP, Windows Vista, OS X 10.6, OS X 10.7, and OS X 10.8 are no longer supported.
Although to be realistic, MS Windows XP and Apple Inc. Snow Leopard machines are getting pretty long in the tooth. For those computers, replacing the entire machine might be the best course of action.