And then you get constantly badgered by notifications and your apps start shutting down because they need a new version of iOS and up-to-date version of app to run.
App developers are making the decision to prioritize newer iOS versions because Apple has been successful at supporting older devices and making updates seamless...
...and suddenly that's a bad thing, despite the security and support advantages.
Apple uses dark patterns and doesn't provide a "stop bothering me" option. I used to get nagged by Apple so I turned on the auto updates just to not have these popups. I guess it worked..