Hacker News Reader

Not yet there isn't. But I can imagine it being made possible, in the same way as EME is allowing DRM on media.

That's true to an extent, except a compiled binary is much harder to decompile compared to what the author has done in the article with obfuscated JS. In future, I imagine more websites will use WebAssembly for this reason.

Well, if they introduced some "special feature" that's available only when you install a certain plugin, I am sure millions of people will do it just because they can get the "special feature."

Browsers won't support plugins for long (extensions yes, but those are as open as websites).

Still, even a binary can be reverse engineered; you see it all the time.

How exactly is that different from non-web applications?

If you have the binary, you can reverse-engineer it.