Beyond that and what sibling comment said, the author is known for creating various languages, so he clearly enjoys doing it and is making this language for himself.
I have never understood why there's always somebody complaining that new languages are unnecessary when a new language is shown on HN. I personally love seeing new languages. I also recently went on a language hunt for something that met a specific need for a side project I'm working on and I came away empty handed because I couldn't find something that met my criteria[1], so I'm always on the lookout for something that might.
[1] In case somebody has any suggestions for me, I want something with Clojure-like immutable data structures as a default (or something similar, at least), is native compiled to reasonably efficient and low footprint binaries (but is not as complex as Rust or Haskell), is a functional language (but with prettier syntax than OCaml, which was almost my choice, but when I started reading example code, its a complex mess of symbols <insert perl joke>). And... it needs reasonable library support... (at a minimum I need to be able to respond to HTTP requests, make HTTP requests, parse and generate JSON and talk to postgres, ideally using SQL and not an ORM). Haskell is probably my best bet, but I don't have the energy to learn all of its complex features.