I think that line is aimed towards people new to all this stuff, hearing "functional reactive programming" being thrown around. The author does seem to know the

I think that line is aimed towards people new to all this stuff, hearing "functional reactive programming" being thrown around. The author does seem to know the 'roots', if you can call it that: "Reactive programming is programming with asynchronous data streams. In a way, this isn't anything new. Event buses or your typical click events are really an asynchronous event stream, on which you can observe and do some side effects. [..]"