I am currently reading the book Adobe Illustrator Classroom in a Book (2020 release)
In the lesson 4, Width tool section(page 463) author has mentioned following about discontinious width point :-
You can drag one width point on top of another width point to create a discontinuous width point. If you double-click a discontinuous width point, the Width Point Edit dialog box allows you to edit both width points.
However I didn't understand this at all, I think the whole purpose of width tool is to increase the width of stroke at certain point.
(a) Why would somebody drop the one width point on the top of another ?
(b) What would be archived by doing so ?
(c) What is discontinuous width point ?