Even if all it was supposed to do is syntax highlighting, different languages are usually highlighted differently and presumably the person maintianing the bindings would need to be a language expert with strong opinions. The options are they either maintain their own mode or a module in `treesitter-mode` which is basically 2 ways of describing the same situation.
Although to address your other point it is quite funny that after 40 years and 29 versions of experimenting in OS design, GNU Emacs is starting to implement syntax highlighting properly for its system text editor.