Going off on quirky tangents can be an effective tool for keeping a reader interested. It reminds me a little of Douglas Adams. He punctuates the hard science fiction with goofy anecdotes to get the reader thinking about the subject from another perspective and to keep them entertained.

It is not a tutorial on how to phish or a vulnerability report, but rather a story about how motivation is potentially more important to phishing than technical skill. Without the casual writing style, the main character (and author) might have seemed more sophisticated, which would have diminished the point of the story.

A joke here and there is fine, but this person injects his jokes attempts pretty much every sentence. That gets annoying quickly.

I guess the threshold isn't the same for all of us, I didn't get irked by he jokes at all... however around halfway through I started wishing for it to be over soon(tm)

Eh, I liked it. Many writers in the tech space are trying to be as concise and clear as possible. If this article had been more 'academic' in that sense I think I would have lost interest after a few paragraphs because, well, nothing in this article is really new. It's just a fun anecdote about the reality of cyber security.

It can be seen as a style that emphasizes just how 'casual'/easy this attempt was, so I think it adds to the content.