fandom confuses me yet again

I thought I had seen the most ill-suited posting venue for fanfic when I encountered fans posting stories to deviantArt, but that has now been surpassed by far: Why on earth would anyone put a ficlet in the tag field in Tumblr?!? And not a five word story or the like either, but something that's abut 350 words accompanying a GIF? I mean, you can post text with a picture, why not do that? Is there a reason to make it a tag? It's actually not a bad Erik/Charles ficlet or gif, but omg the formatting...

And connected to this another Tumblr question: the post I linked above to illustrate is a reblog of the story in the erikandcharles Tumblr, because the original post you get to when clicking that reblog has apparently been deleted. So if others reblog your posts/pictures on Tumblr the reblog posts remain, and you can't delete your content? What about edits, i.e. say I posted a sketch to Tumblr, it gets reblogged by someone, then I notice that the hand of the character has the thumb on the wrong side or a similar error (don't laugh, that has happened to me with pictures) and edit my post with an upload of a corrected version. Will the correction propagate through the reblogs? Obviously there are pros/cons either way, i.e. if it does affect the reblogs you can do effective corrections, however because the nature of Tumblrs it would also open an easy way to abuse/spam or rickrolling, in that someone could post something attractive and pretty, wait a bit, then edit to shock image or the like. So would you have to live with wrongly thumbed hands forever when posting to Tumblr?