By implementing it at the beginning of a UX paradigm cycle when the numbers of users are small, curious and in learning mode. Like how right-clicking was introduced when the number of Windows users was like 1/1000 of the number of the peak number of Windows users.
You don't implement it during/after peaking of said cycle. That's some crazy level of delusion/arrogance. Turns out not even Apple can do pull that stunt.
Most computer users still don't use middle-click/scroll wheel click, or even the back/forward buttons and they're almost twenty years old.
By simply pointing at another hard to train piece of hidden functionality and saying "what about THIS?!" you haven't really proven anything, except that with enough forced training anything can become common knowledge.
3D Touch is exactly like right click, but they're also competing against implicit training via passed users of Apple's own products, other touch devices, and even other computing (since no other platform has anything like 3D Touch).
They offered no on-screen guide or tutorial when it launched.
You don't implement it during/after peaking of said cycle. That's some crazy level of delusion/arrogance. Turns out not even Apple can do pull that stunt.