I, for one, am not excited about this. It's a "oh, that's neat" feature visible only to developers, but it is not enabling anything groundbreaking for the end

I, for one, am not excited about this. It's a "oh, that's neat" feature visible only to developers, but it is not enabling anything groundbreaking for the end users, so it isn't making webapps more competitive with native. We still need iframes for 3rd party embeddable components, and for 1st party components we have good enough solutions, and the tendency seems to be abstracting the DOM away. Web Components keep taking a lot of spec and implementation effort that could be spent on something with a bigger impact (ServiceWorkers in iOS? Transactional DOM that doesn't jank/layout-trash? Activities/Intents/Scopes for native-like sharing?)