I do understand copyright applying to avatar and background images. If someone is using someone else's artwork or photography for either one of these, I can see

I do understand copyright applying to avatar and background images. If someone is using someone else's artwork or photography for either one of these, I can see a DMCA notice coming in and being honored. I suppose there could also be some sorts of material where 160 characters could exceed quoting for fair use. Such as haikus. I do not understand all the takedowns because of mere mentions of pirate sites, or inclusion of their names, or even linking. Has linking really become illegal? That was one of the nightmare scenario people were worried about some years ago, but which was dismissed as something that would never happen. I completely and totally contest that a URL to an actual site is a copyright violation. (Barring the extreme cases such as a URL containing a haiku, but that doesn't seem to be the case in any of the incidents listed.)