Latex seemed arcane coming from the background of HTML but it was pretty easy to pick up and is human readable.
Aside from the markup language itself, what is cool about TeX is its versioning. Since the idea is that at some point it does meet all of its goals it is essentially approximating its own perfect form. As a result as it gets closer to that goal its version approaches the value of Pi [2]. The current version is 3.141592653.
Tex has been around for 47 years so if you are looking for stability, look no further.
[1] https://en.wikipedia.org/wiki/TeX
[2] https://www.preethamrn.com/posts/piver
P.S.: manpage format is also quite simple to learn and it is always a really good addition to any CLI tool.