I wouldn't say "the functional crowd won"—that's certainly not how I would write the code, and it's not the style that high-profile projects like Servo typically use. Rather, the author clearly prefers functional style, and Rust (like most modern languages) allows you to write in that style if you wish.
Of course. This example was given to show expressiveness. For production-level code, you would break it up more so pieces can be tested individually (as pointed out in another comment).
