Emacs, at least, already provides primitive parsing / heuristics that work reasonably well for most languages. See the example in the link I posted above: All I had to do was customise the colour and font-weight of various things already recognised by Emacs: function-name, variable-name, type, etc.

Maybe what I don't understand is all the effort people put into making pretty themes for their editors --there are millions of these themes out there-- and almost all of them insist on highlighting (drawing attention to) the language's keywords of all things. The least important part of any program.