Your second premise doesn't hold for all browsers: links cannot display Blogger pages; Firefox with NoScript cannot display Blogger pages; the Tor Browser with high security cannot display Blogger pages.

The Web is, fundamentally, about resources — documents — and their state, not about behaviour.

> JS _is_ the Web just as much as HTML because all browsers support it.

No. They. Don't. eww doesn't. w3m doesn't. lynx doesn't. links doesn't. elinks doesn't. Firefox with NoScript doesn't. The Tor Browser with high security doesn't. That is the reality.

The reality is also that allowing JavaScript exposes users to severe privacy and security threats. Disabling JavaScript is the only way to control those threats.

Every site which requires JavaScript to function is like a serpent tempting a user into giving up his privacy and security. That is the reality.

If you want to serve an empty, broken page as a first impression, you can. I strongly recommend against it because it makes your site look half-finished, poorly designed, and generally unprofessional.

> available in the browser

That isn't always true. You don't know anything about the browser a priori.

> make a better experience

Of course. Javascript can add nice features, which is why you progressively enhance the page to add features when the underlying requirements are available. Do you skip the check for NULL when calling fopen(1)? Checking for errors is always important. On the web, this means you should gracefully handle problems like missing javascript (intentionally or otherwise) or other resources.

> Making UIs respond faster

Requiring two additional HTTP requests (one to load javascript, and another to load the actual page content) isn't making the page faster. After the first request your javascript will be available most of the time for partial loads in any case.

> interactive content

That is rarely a good idea, but it's your page so do what you want. Progressive enhancement doesn't affect this at all.

If it doesn't work without JavaScript, it's breaking the web.

I have absolutely no problem with progressive enhancement. I have absolutely no problem with choosing to enable JavaScript when it makes sense. I have a problem with requiring a privacy-destroying technology in order to consume content.

I think that some of them make sense, but many many many would be better implemented as RESTful apps instead. Once the REST layer is written and works without JavaScript, implementing an enhanced version which requires JavaScript and minimises redownloading of new data is relatively easy.

Imagine a chat app. The pure-HTML version could serve a chat message at /chats/{partner}/{message-id}, with a prev link to the previous chat; it could serve a chat sequence at /chats/{partner}/{message-id}?history={length}; it could redirect /chats/{partner} to the most recent message in a sequence. A form could easily enable POSTing a new message to the chat.

Once all that's done, it's dead-easy to write some JavaScript which ties it together in a single-page app. Instead of requesting each message as text/json, the JavaScript client could accept application/json (or another format, if you like). It could subscribe to a WebSocket or server events. It could do anything — but the basic HTML-based app would still work, and be usable from a command line, from a simple phone, from anywhere.