I mainly made it for stuff like division where you have to type in \frac{}{} every time. So instead of typing \frac{x}{3} you can just type x/3 and get the same result.
I was surprised to learn just the other week that `\frac x3` will give what you want, in Latex.
I remember being surprised when I first saw \frac12, and I was like "that works?". The response I got was "of course". In retrospect, I admit that's the right answer: once you get TeX well enough, it's obvious.
This works for a lot of stuff. If you are only giving one input it'll work. So things like "\sin x", "x^2" \frac12" work. Interestingly you need a space in the sin example but not in the others. But "x^12" is the same as "x^{1} 2". So be careful with the shortcut.
It's not surprising if you know how TeX lexes things, which you should never ever learn.
Often I do want to output x/3; is there a way to do that here?
Sorry I haven't thought of a good solution for that yet, but if you really want to write a / you can do: "x text{/} 3"