Except unlike WebAssembly this one is actually useful. WASM enters a domain full of existing universal bytecodes that all failed to become truly universal because the actual assembly is never the hard part to get portable, it's the API surface. Which WASM doesn't even pretend to attempt to handle, unlike a Java or C# which ship pretty fat bundled libraries to abstract most OS differences.
Meanwhile on the GPU front you don't have much in the way of large, good middlewares to abstract away the underlying API. OpenGL used to be OK at this, but now neither platforms nor Khronos wants to touch it. Vulkan is "portable" but it's like writing assembly by hand, it's ludicrously complicated. WebGPU fills the role of essentially just being GLES 4.0. It won't be fast, it won't be powerful, but it doesn't actually need to for the long tail of things that just want to leverage a GPU for some small workloads.
Meanwhile on the GPU front you don't have much in the way of large, good middlewares to abstract away the underlying API. OpenGL used to be OK at this, but now neither platforms nor Khronos wants to touch it. Vulkan is "portable" but it's like writing assembly by hand, it's ludicrously complicated. WebGPU fills the role of essentially just being GLES 4.0. It won't be fast, it won't be powerful, but it doesn't actually need to for the long tail of things that just want to leverage a GPU for some small workloads.