MV arises naturally. You can run the entire application logic without UI components, and you can test it that way also.
Other abstractions are designed similarly to allow tests against pieces of the internal API in total isolation, though separated on different lines. Maybe you have transient state stored in view models while persisted state is stored in models. The isolation only helps as size grows, and it can keep size under control mostly by having a good data model for what each component / layer / aspect actually does.
It makes it easier to rewire everything when you start with a switchboard. UI changes are either "Oh my god we're going to have to re-write so much stuff if we do it that way!" and you wind up not making drastic UI changes or "Sure, we can make that thing tickle the controller instead of that other thing."
Other abstractions are designed similarly to allow tests against pieces of the internal API in total isolation, though separated on different lines. Maybe you have transient state stored in view models while persisted state is stored in models. The isolation only helps as size grows, and it can keep size under control mostly by having a good data model for what each component / layer / aspect actually does.
It makes it easier to rewire everything when you start with a switchboard. UI changes are either "Oh my god we're going to have to re-write so much stuff if we do it that way!" and you wind up not making drastic UI changes or "Sure, we can make that thing tickle the controller instead of that other thing."