It is very relevant for total novices. When someone has no concept about programming, this is the fastest way to "here are the barest basics, and you have already written a program."

Quick sort means nothing to someone who does not yet grok compiling and output, much less sorting as an algorithmic process.

Question isn't whether "hello world" is obsolete, it's the level of knowledge of the author. A rank noob needs to see the simplest possible program, not the highest density functionality.