All properties within the appearance section of the Path Properties are pre-filled with default values, with the exception of the Dash Array.

Because of this, it is not at all obvious to the user what value format the Dash Array takes, making it potentially not possible to be able to use this feature.
Personally, I was not sure if it was a single number, multiple numbers, whether I had to click and drag like a slider, whether I had to input multiple numbers separated by dashes, etc...until I eventually found out what the format was.

Although I agree with the fact that this should not have a visible dash array by default since most strokes created will not be dashed, it would still be helpful to at least demonstrate how to construct a Dash Array by inserting a default value of:

Dash Array: 0,0

This value would not render a dash on the stage, but would at least demonstrate that an array is constructed by at least two numbers, separated by a comma.