I'm glad you're pointing this out because not only are these old insights, but I'm also pretty sure I've seen variations of this blog post years ago on even HN already.
The author acting as if they discovered this independently had me feel the exact same way. Kinda irritating and almost ... disrespectful? Not sure of the right words to describe it tbh
Fabrice Bellard published this in 2023: https://bellard.org/ts_zip/
> The ts_zip utility can compress (and hopefully decompress) text files using a Large Language Model. The compression ratio is much higher than with other compression tools.
It's not only an old idea it's been totally done already.