MVC is a design pattern that encourages separation of concerns. It was invented in 1978, and was generalized in the 80s. Smalltalk was the first language to make extensive use of this design pattern for the creation of user interfaces.
Objective-C, being heavily influenced by Smalltalk, then inherited this design pattern. AppKit and UIKit are also built around it.
While one could argue that other patterns can be just as efficient (or more so), MVC has the benefit of being widely understood by many developers, independent of their language of choice. MVC is widely used and is available in all object-oriented languages.