Purpose of duplicate-selection key?

In recent versions of Kakoune, I see that + in normal mode “duplicates each selection (generating overlapping selections)”. I tried it and it does work, but what is the use case of this command? I could not think of any good reason for using this selection-duplication mechanism.

It’s also something I don’t fully understand why it’s there, since it breaks the orthogonal design…
Imagine that you want to type ../ 10 times:
../../../../../../../../../../
you could either do:

  • i../<esc>x_y9p (select the line and paste it 9 times)
  • i../<esc>x_9+yp (select the line 9 times and paste the selections once)
  • 10+i../ (duplicate the selection 10 times and just type ../, arguably the best one)

Note that the behavior of + is a bit particular. A count will generate that many selections, but pressing + subsequently will duplicate the selections at each press: 2 → 4 → 8 → 16 and so forth.

10+i../ (duplicate the selection 10 times and just type ../, arguably the best one)

Before + was added, this was already possible as 10o<backspace>../

However, it seemed non-orthogonal to have to insert newlines and backspace over them, so a new key was added that just set up the “overlapping cursors” state directly.