> Isn't the point of the article to describe how an engineer would create such a tool?

Honestly, no, because the tool that it's suggesting how to write isn't one that will even come close to doing a good job.

If you want to write such a tool, the first thing you need to do is to understand what the correct answer is. And to do that, you need to sample your input set to figure out what the correct answer should be for several inputs where it matters. There's unfortunately no easy way to avoid that work; universal charset detection isn't really a thing that works all that well.