Sunset had hoped that showing the Rainbooms what she'd written about them would remind them of the good times they'd had and the kind of person she'd become. That if she could just get them to listen they'd realize she would never betray them.
She was partially right. Fluttershy and Rainbow Dash believed her, but --with no likely suspects-- Applejack, Rarity, and Pinkie Pie were unmoved.
The Rainbooms split. Sunset's group become targets for the students of CHS to vent their frustrations on. And Anon-a-Miss keeps posting.
Yeah, another Anon-a-Miss story. It comes from a lot of things. A lot of it is just trying to answer some, but not all, of the questions posed by Dainn when he wrote his seminal work:
But what if things happened differently?
What if Sunset never figured out who Anon-a-Miss really was?
What if her friends refused to listen after her little chat with Twilight?
What if Sunset's friends did listen but Sunset didn't figure out (and the CMC didn't confess)?
The conversation in the comic is open to interpretation, but it looks to me like Sunset was able to convince Fluttershy and Rainbow Dash of her innocence but failed to convince the other three.
And what happens then? What happens when the guilt of Sunset Shimmer is a split decision? What if things don't die down or escalate but instead drag on into the new year without a clear end in sight? What does Scootaloo do when Rainbow Dash is the one being bullied in the halls?
So many stories put their major point of divergence at the exact same place: Things might differ before that point, but they don't go off the comic's rails until Sunset goes to Sugarcube Corner / The Sweet Shoppe in a last attempt to get the girls to listen to her, and it utterly fails.
This pushes things back just a page and a half, but that little bit of difference will make everything change.
(Main Seven tag is because I can't tag six characters. There is no plan to include Sci-Twi at this time)