Earlier quoted context omitted.
I have a phone that is 3D Touch capable and I never use 3D Touch at all . In fact I mostly avoid using it; it's Those Useless Options That Sometimes Pop Up If I Press Too hard On A Thing. It's on par with OSX's "some menu items change if you hold down alt while they're open" behavior. Aggressively obscured.
Then turn it off (Settings, General, Accessibility) Although lacking discoverability, I personally find it very quick, useful and natural in a couple of use cases: acting on notifications, keyboard cursor movement and selection, (sadly defunct) app switching, on Apple Music track listings.
Oh right, I use the keyboard cursor movement all the time.
Haven't found a single other place where it does anything I find useful.