Let's say you are an FR user, and you don't want it and don't install it. Could others out there who have it be discussing or even outraged about something you posted and be bandying your screenname about without your knowledge?
Yeah, sure they could ... which is a good reason to have it ... just to be aware.
That’s the thing about a ‘really’ open and free speech plug-in ... people can talk about you, too ... but that’s to be expected.