Until the apps you depend on force you into an os you can't upgrade into. Its crazy like there are still security updates and devs will pull the plug, and twist the knife cutting off api access for their old software.
Social media (snapchat especially) and rideshare apps are the biggest offenders in my experience. I tried to get an uber on this phone and it wouldn't let me use the old uber version already on it, and wouldn't pull a newer one from the app store from the iOS limitation. I guess they have a mobile website but I didn't think of that, just called a lyft instead.