This is a bit pedantic. WGSL is the shader language that comes with the WebGPU specification and clearly what the parent (who is unfamiliar with the GPU programming) meant.

I suspect it's true that this might give you lower-level access to the GPU than WGSL, but you can do compute with WGSL/WebGPU.

Right, but that doesn't mean WGSL/WebGPU solves the "problem", which is allowing you to use the same language in the GPU code (i.e. the shaders) as the CPU code. You still have to use separate languages.

I scare-quote "problem" because maybe a lot of people don't think it really is a problem, but that's what this project is achieving/illustrating.

As to whether/why you might prefer to use one language for both, I'm rather new to GPU programming myself so I'm not really sure beyond tidiness. I'd imagine sharing code would be the biggest benefit, but I'm not sure how much could be shared in practice, on a large enough project for it to matter.