To be clear, the OP is talking about expansion of the platform itself, not libraries. In my view, the real development burden is on the browser vendors, not th

To be clear, the OP is talking about expansion of the platform itself, not libraries. In my view, the real development burden is on the browser vendors, not the site authors. A site can always choose not to use some new feature. Imagine if the web were designed so that each site were -- to borrow from Alan Kay -- a "fully functioning computer." It wouldn't be the web as we know it. A site could ship ship some fundamentally new behavior, and if other sites liked it, they could modularize and cache it. The focus in this alternate world is on building a system that is agnostic of its specific usage -- kind of like the Internet. A library system for the web would be the best possible outcome. But that's not what the web is. It's a document viewer with featuritis. That's okay. It's ours. We're happy to have the curses of success.