I see a lot of people who reject the idea that Emilia is Satella because it would hinder Emilia's development!

  
I see a lot of people rejecting the idea that Emilia is Satella because they feel it would undermine Emilia's character development.

I don't entirely agree, though. Let's be clear: if Emilia is Satella, then Emilia's entire struggle proving she isn't the Witch of Envy and deserves to be judged on her own actions is called into question. If she actually is the Witch, then the discrimination she has faced since birth would be, from a purely pragmatic standpoint, "justified." That would destroy the story's message of tolerance.

However, for this theory not to ruin Emilia's character, Tappei would need to frame it not as an inevitable fate, but as a final obstacle to overcome. The most popular theory is that Satella is a future version (or an alternate timeline version) of Emilia who "failed" and succumbed to despairlikely by becoming too dependent on Subaru. The Emilia we follow now thanks to Subaru and the emotional growth she gains throughout the arcs would be the one with the mental strength to avoid becoming the Witch of Envy, thereby breaking the time loop.

And above all, if Emilia isn't Satella, how do you explain the potential romances involving Subaru with both Satella and Emilia? It would be weird, wouldn't it? Subaru would essentially be with the same "skin" twice.

Refusing the idea that "Satella could be Emilia" is sheer madness!