I'm always curious as to why more people don't go with a hybrid approach. For a lot of my projects, it ends up being the simplest and cleanest solution. Maybe it doesn't really scale well when you have a lot of people working on the codebase that may or may not be familiar with both the backend and frontend, but when it's a one or two person project, I don't see the issue with it. It certainly keeps things simple and prevents duplicated logic.

Exactly; for regular apps with little interaction needs, I start with a pure Rails back-end, and mix KnockOut.js only where relevant (for instance), or not at all.

For more UI-dynamic apps like https://www.wisecashhq.com, I go Rails JSON back-end + html rendering for skeleton, and KnockOut.js for the interactivity.

Now that DHH advocates "his way or the highway" isn't really a surprise :-)

That was my immediate thought too. In the example cited the client side todo consumed a json list of all todo items. The server side is still going to be MVC just exsposing json instead of html.

Maybe I'm just splitting hairs, in general I agree with the author's premise.