I think you need to take into context the history of browsers vs. operating systems... operating systems were always a platform, while browsers started as consumers of an electronic document standard.
That being said - I agree with your ideal, and I don't think it's far off. HTML as a view engine combined with WASM as a cross-platform runtime can enable truly cross-platform, industry-standard native applications. I think it's only a matter of time until Electron apps morph into cross-platform native apps running off of a thin WASM layer. Once those are available, then the OS vendors will have a huge competitive advantage if they develop fast native WASM runtimes.
That being said - I agree with your ideal, and I don't think it's far off. HTML as a view engine combined with WASM as a cross-platform runtime can enable truly cross-platform, industry-standard native applications. I think it's only a matter of time until Electron apps morph into cross-platform native apps running off of a thin WASM layer. Once those are available, then the OS vendors will have a huge competitive advantage if they develop fast native WASM runtimes.