There's something real in the impedance mismatch argument that I think the replies here are too quick to dismiss. The browser's programming model is fundamentally about a graph of objects with identity, managed by a GC, mutated through a rich API surface. Linear memory is genuinely a poor match for that, and the history of FFI across mismatched memory models (JNI, ctypes, etc.) tells us this kind of boundary is where bugs and performance problems tend to concentrate. You're right to point at that.

Where I think the argument goes wrong is in treating "most websites don't use WASM" as evidence that WASM is a bad fit for the web. Most websites also don't use WebGL, WebAudio, or SharedArrayBuffer. The web isn't one thing. There's a huge population of sites that are essentially documents with some interactivity, and JS is obviously correct for those. Then there's a smaller but economically significant set of applications (Figma, Google Earth, Photoshop, game engines) where WASM is already the only viable path because JS can't get close on compute performance.

The component model proposal isn't trying to replace JS for the document-web. It's trying to lower the cost of the glue layer for that second category of application, where today you end up maintaining a parallel JS shim that does nothing but shuttle data across the boundary. Whether the component model is the right design for that is a fair question. But "JS is the right abstraction" and "WASM is the wrong abstraction" aren't really in tension, because they're serving different parts of the same platform.

The analogy I'd reach for is GPU compute. Nobody argues that shaders should replace CPU code for most application logic, but that doesn't make the GPU a "dud" or a second-class citizen. It means the platform has two execution models optimized for different workloads, and the interesting engineering problem is making the boundary between them less painful.