As I said, I don't see any connection between that episode and "Cupcakes." There's no depressed, flat-maned Pinke in cupcakes. And while Pinkie was certainly a little "out of it" after thinking her friends had betrayed her, she wasn't remotely dangerous or evil. The worst thing she contemplated was not inviting her "former" friends to any more of her parties. There's still a gulf between that and "Cupcakes" (which, as you pointed out, predated the episode).
I have no objections to horror fan fictions. My objection was solely to the identification of the character in the fan fiction with the canon character on the show.
They have been doing a ton shout out to the fans lately, hell the last scene of the Season Finale alone has so many the fandom is still finding them.
There are some fan conventions I would never want to see as "shout outs."
U No Like Princess Molestia!?
character in the fan fiction with the canon character on the show.
Nothing was better than the Sweet, Sweet smell of Fan-fiction burning after the Luna-Halloween Episode, ah, I loved it how her Canon self with nothing like the Fanfics!