It does exist, and importantly, existed earlier, and has effectively no configuration. This means its usage is significantly more, and more internally consistent. Frankly I am a bit jealous, but I only have myself to blame here :)
There are people who like gofmt and dislike rustfmt.
I live in JavaScript land mostly, which is the wild wild west when it comes to "the way to do things," so rustfmt is still many times better than, say, prettier and eslint. It exists AND it's part of the standard tooling!
There are people who like gofmt and dislike rustfmt.