The particle-wave duality has to be accepted as our reality : electron interference, photoelectric effect.
And it has very direct implications : how can one think of a little ball of matter ?
It is simple in a sense : it's just not exact. But what can we do?
Thus we come to think of particles as spread out in a sense, manifesting itself in the interactions.
Equipped with the math of it, consistent interpretations start making sense.
The uncertainty relations rounded the development of basics of quantum theory.