For a general audience this is good advice.

This article was written for a specific audience who follows this blog because they know the term. If you start spelling out fundamental acronyms it makes the content look more basic and general.

This always upsets the general audience who stumble upon the article (like this) but it wasn’t meant for a general audience. CTF is extremely well known and the people who would be interested in this topic would wonder what’s happening if it was spelled out. It would be so odd that it would probably attract accusations of ChatGPT writing.