I find it undesirable to let individual documents (or applications) to change/control fonts and colours in general, and usually restricting font changes by webs

I find it undesirable to let individual documents (or applications) to change/control fonts and colours in general, and usually restricting font changes by websites in FF, but sometimes noticing that some websites still manage to mess up the fonts by adjusting finer rendering options, as described here. Though it appears to be an even more general trend than that: reinventing and worsening built-in web browser functionality with JS is another common activity, as non-web software is prone to reinventing system functionality (or settings), and I usually imagine that the intent there is to "fix" things too (or at least to make them look prettier). I wonder how much these "please stop" blog posts help: seems like they are supposed to raise awareness among developers, maybe to point it out to those who didn't think of it, but IME much of the awkwardness, especially in the UI, comes from non-tech-savvy client/user/management requirements: things must look good enough in a presentation, on their machines, and/or on common machines and systems at the time (though an argument can be made that it's the priority in many cases).