I think that this article is one of the worst I have seen.
Why are they taking about AJAX like it is me? Many languages have a lot of libraries? Debugging using breakpoint is in many languages? And the same for unit testing.
Having the client execute the script does not save bandwidth, but increase most likely if you don't cache..
It's clickbait, plain and simple (what do you want from dzone, king of interaction spam for devs). also, most of the functionality of AJAX came from the browser DOM, not the language.