Because it would have to be entirely coded by hand and I honestly don't think there'd really be a way to do something like that. It would require the site to first of all recognize that you have a microphone, record the clip, save it to the server, and then fetch the location and post it. Even if it WAS possible, it'd be incredibly hard to do and take a loooooooong time to come up with.
If something like that was possible chances are you'd've seen it on another site before and honestly, I certainly never have.