There are two scenarios.
First, there are cases where you want to temporarily switch between height-first and width-first layouts.
Suppose the window is split horizontally into two sections, with the right side further split vertically. If you want to switch to a layout where the window is split vertically and the bottom section is split horizontally, this would effectively be a 90-degree rotation.
It is not easy to achieve this by toggling between moving the window up, down, left, or right and changing the split direction.
The second scenario involves correcting a situation where a new window has resulted in an unintended split.
For example, if a new window has split the vertical side opposite to the intended side in a left-right split, and you want to swap the left and right sides, this would be equivalent to a horizontal flip.