There are a few problems with the traditional way of using computers.
First of all, end users have to install and update every component in the system. Due to the complexity of components, defects are bound to be present. However, unlike hardware components, it is relatively easy to fix most defects of software components, everything from drivers to application programs.
This is why all systems (Windows, Linux, OSX, etc.) need to be updated once in a while. Most updates fix existing problems, while some may extend features of a system. If such updates are not installed in a timely fashion, a security flaw or vulnerability can be exploited.
The second problem is that even the hardware needs to be replaced once in a while. This is because new OSs and application programs assume more resources, which makes it impossible to install and run newer application programs on older computers. This makes it necessary for end users to upgrade or build new systems every few years or so.
When an end user purchases a new system, it is a great deal of hassle to reinstall all the application programs and restore all the user data onto the new system.