I agree. One addition to this is that I configure my themes so that heading-like constructs are displayed in bold; in C that would be function names in function

I agree. One addition to this is that I configure my themes so that heading-like constructs are displayed in bold; in C that would be function names in function declarations (and definitions), and in HTML say, it would be the content of <h1> to <h6> elements. The motivation for this is the same as for highlighting headings in ordinary prose; it makes it easier to get an overview of where you are in the text.