What you're describing existed. It was called plugins. Back in the Old DaysTM, browsers just rendered documents, and if you wanted whiz-bang interactivity featu

What you're describing existed. It was called plugins. Back in the Old DaysTM, browsers just rendered documents, and if you wanted whiz-bang interactivity features, you ponied up for a copy of Macromedia Flash. Or Director, if you wanted more features and could tolerate it's long plugin download times. Or, if you were more developer-minded, you wrote Java Applets (or, later on, Silverlight apps). Things like Flash didn't ultimately supplant the web, but this is primarily due to three forces: 1. Adobe's insistence on new Player features over security 2. Google's insistence on adding new features to HTML5 via Chrome to support internal business goals 3. Apple's insistence on killing plugins dead to keep the iPhone secure (and cut Adobe out of the developer tools market) The only vestige of plugins that remains are EME implementations (so-called "HTML5 DRM"), but that's purely due to legal reasons. Had HTML not grown to supplant the use cases of plugins, I think it would have stuck around, if only because all those plugins required significant expense to make use of. I doubt Adobe would have, say, tried to make a web browser in Flash just to cut the HTML middleman out.