Updates are issued frequently to address newly discovered security issues and to accomodate new hardware and software coming onto the market. Windows 10 is supposed to be a one size fits all operating system so everybody has to update whether it is necessary for their particular machine or not.
If you never connect a computer to the internet or update any of the components, it could quite happily run with the initially supplied installed software forever, never needing an update.
Even Linux software needs to be updated, although the user has rather more control over what gets updated and when. That assumes the user has the necessary knowledge to recognise security risks and how to avoid them. Otherwise Linux can present even greater security risks to your data. The most common mistake being users using a root access password for normal day to day tasks, because it gives instant access to all the features of the computer and operating system.
For all their proprietory systems and expense, Apple seem to have got the concept of turn key computing with a decent level of security down to a fine art.
If all you want to do is browse the Internet and send emails, a tablet computer such as the iPad is all most people need. They too get regular updates, but because the hardware and software is controlled by a single company, there are far fewer problems than with any other type of computer as far as my personal experience is concerned.