So, as a code example, fine---but I'd caution against actually using this with your friends unless you know they're okay with it. They will be acting under certain social expectations with regard to when and how people can see their typing notifications based on when and how they were able to see them before, and if you tweak your way into getting more access without your conversation partners knowing it beforehand,…
Facebook users are apparently broadcasting the fact that they are typing to their conversation partners, why should you ignore that information? If you don't like that, disable that feature, or complain to Facebook if it is not something you can disable yourself (or don't use Facebook). It can't hurt to raise some awareness of what you are invisibly broadcasting in terms of data on-line. (I always liked how this feat…
Put another way, your statement makes perfect sense if you assume all software is actually a User-Agent in the traditional, ideal sense. But this isn't so, because even programmers don't generally have the spare cycles to rewrite everything they come in contact with, and non-programmers have an even more vanishingly small chance to do anything about it. Agency in the digital world is inevitably shaped by other people's decisions as represented in software, and social agency is shaped by how that software presents itself not just to you but to the people you're communicating with through it. When the state of the software doesn't exactly match the state as visible to the participants, the latter state prevails in a social context, and it's the responsibility of a polite conversation partner to not mess around behind the curtain unless you already know you're welcome.