Not everyone does it. Personally, I don't see the point of reblogging either but I do post original stuff ie. photography/creative writing and never ever reblog, though I do find the ocassional memes/Facebook captures highly amusing. But the reason why I use it is because Tumblr is relatively user friendly for those who are technologically inept/already have friends on so it's convenient.
I'm yet to see enough people who actually blog to change my view. Quite literally every single time I'm referred to a tumblr by a friend or person I know, it's just pictures of exotic cars, famous people, shoes, clothes, those pictures with text on it ("i'm not mad i'm just etc" - I find completely pointless), memes, baby animals, sunset/sunrise/night, scenery, couples and all this other stuff. And a lot of them have a purple tint over them to make them look old - clearly edited one way or another. I just see no substance to it

Oh and my tumblr is 4agze.tumblr.com - made it because a friend wanted followers. She then proceeded to delete her account the following week
