And if we were all using XHTML1.1 now instead, yes, your parser would be easier, except all the richer content would be in flash, and all the web apps would be desktop applications, and you wouldn't be able to parse that at all, even with a full browser.
You are acting like everyone would just stop and wait for you to make your dream implementation that's ideal - that's not how the world works.
WHATWG was an admission that we can't stop it, so we might as well embrace it. Embracing it has resulted in browsers being far more consistent, and new features being a shared part of the web platform, and not siloed off in plugins and other platforms. That's why W3C is irrelevant now.
You are acting like everyone would just stop and wait for you to make your dream implementation that's ideal - that's not how the world works.
WHATWG was an admission that we can't stop it, so we might as well embrace it. Embracing it has resulted in browsers being far more consistent, and new features being a shared part of the web platform, and not siloed off in plugins and other platforms. That's why W3C is irrelevant now.