For a couple of reasons:

* You need have a clean architecture, so starting "almost from scratch" * Knowledge about performance (for Rust and for build tools in general) is necessary * Enough reason to do so, lack of perf in competition and users feeling friction * Time and money (still have to pay bills, right?)

I believe it goes back a few years to originally being just oxlint, and then recently Void Zero was created to fund the project. One of the big obstacles I can imagine is that it needs extensive plugin support to support all the modern flavours of TypeScript like React, Vue, Svelte, and backwards compatibility with old linting rules (in the case of oxlint, as opposed to oxc which I imagine was a by-product).

Because Rust makes developers excited in a way that C/C++ just doesn't.

It takes a good programmer to write it, and most good programmers avoid JavaScript, unless forced to use it for their day job. in that case, there is no incentive to speed up the part of the job that isn't writing JavaScript.