[Tainnor]

UTF-8 works with xetex, and both it and latexmk are easily installable from package sources on Ubuntu (and probably other distros).

You do raise some valid points, but most people don't really use those programs you've mentioned (I've only ever used minted), and you have to consider the insane breadth of things (often very specific to particular scientific disciplines) that LaTeX and its ecosystem are dealing with. Plus, IMHO it's a bad choice to abandon LaTeX's maths notation (despite its obvious weaknesses) entirely because the institutional inertia here is incredibly high; it's used basically everywhere even outside LaTeX itself (MathJax, Discord bots, several online forums, etc.). Mathematicians (and students / researchers from adjacent disciplines) have become _really_ used to it. And unlike programmers, researchers don't usually need or want paradigm shifts every few years.