Shouldn't this be considered "fair use"? A bunch of guys find some pictures on the internet. These pictures are not the originals but low-res jpegs. The picture

Shouldn't this be considered "fair use"? A bunch of guys find some pictures on the internet. These pictures are not the originals but low-res jpegs. The pictures are saved on their machines (by the browser). Then the pictures are uploaded to Twitter. The source/photographer is provided with every picture (if info. is available). I don't understand how photographers are losing here? They are getting free publicity from the pictures which were already accessible to everyone.