So I develop my sites in Visual Studio. Every once and a while I would have two characters get displaced, more specifically, swapped positions. I figured that while I was editing, I would leave the window open and continue to do something on my second monitor and then come back and accidentally highlight and drag a letter one position over. I couldn't believe I was doing this so often. A colleague asked me a question yesterday that required me to look something up. I went over the the other monitor, and without giving the browser focus, and I hit control-t to open a new tab. Where I then realized that control-t swaps characters around the insertion point. I was very relived to find this out.
Anyway, I could have done without the story, but this question remains. What in the world is this feature used for? I cannot imagine a scenario in which I would use this feature.