A bridge only works when everything is properly lined up.
We don’t expect anyone to be able to build a successful bridge without some sort of specification that explains where it starts, where it ends, and how and where all the components in between are expected to connect up.
But somehow we expect our people to construct successful customer experiences time and time again without any kind of guide to how they are supposed to be.
A rudimentary sketch is better than nothing.
But much better to have a proper set of drawings to follow.