> If you look at all the large Javascript frameworks, the increase in hardcore software engineering approaches taken to the front-end are an interesting signal. We have MVC in the front-end, we have MVC in the backend. Why have two MVCs if you can write an isomorphic application and have one?

That is not necessarily a language oriented concept. JavaScript can run on the front-end and back-end having an MVC architecture at both points. A better question is why a developer should wish to impose MVC at all at either point?

These concepts become easier to reason about when the software runs at a single location using an HTTP service (on localhost) to talk amongst its clusters. It is just a multiprocess application with the bits running asynchronously from each other.

When one (or more) ends of the environment are distant factors change drastically. First, you don't control the remote environment. You are completely at the mercy of what the user is willing to execute and they may modify your application in ways you do not anticipate. Secondly, there is a delay between distant ends.

Regardless of the application or language in question the environmental and security considerations at hand will continue to impose a separated JavaScript-like web application.