So what? Forums already existed before HN. Cars already existed before Tesla (or Toyota or GM or BMW). Discord wasn't the first chat app. Google wasn't the first web browser.
There's no requirement to avoid doing anything anyone has ever done before!
Except for the fact that the blog post literally starts with the premise that there are no Rust job boards out there. That's simply not the case as I pointed out in my earlier comment.
That said, I hope this project succeeds by making it easier for Rust developers like myself to find jobs!
Question for the creator: how do you plan to compete with the existing Rust job boards?
Once you get more jobs on the site, it would be nice to have a bit more compact of a UI so it's not necessary to do so much scrolling.