Twilight’s natural skill set is magic. Magic is minute precise control of the world. This explains her natural micromanagement bias.

Twilight’s assigned role is friendship. Friendship is about allowing, trusting, and giving equal power to others.

Both ideas have a contradictory fundamental mind set.

If Twilight does not keep in mind that friendship/allowance overrules magic/control she will collapse back into control. Successful control leads to elitism and therefore evil.

I wonder if Celestia set up Twilight as Princess of Friendship to counter her natural magic/controlling/elitist leaning inner nature.

Having said all that, no one expects Starlight or Trixie to be skilled in the Magic of Friendship, but everyone expects Twilight to have mastered Friendship (being the Princess of it). Twilight fell the farthest, and so for me is the most to blame. Trixie provided an opportunity to Twilight to choose her path and Twilight chose the wrong one, see above. Starlight, being significantly more humble than the other two, had the most success because she was the most allowing/friendly, despite significant odds.

Well done Starlight.

@headlessrainbow
There’s probably a fallacy somewhere here.Better check Wikipedia

1. She is a person who makes tons of mistakes but never has to experiance any repurcussions
    
   or
    
2. She is too often considered the solution to everything even when it makes no sense.
    
   or
    
3. She has more good forture then 99.9999% of people could ever have, and she solely profits from many of the team efforts
    
   Its usually something along those lines. (#2 might be confused with the initial assumption, but it most certainly isn’t the same) Whether either or any of these apply to the definition of Mary Sue, if there even is an exact definition, its sort of irrelevant. All of these apply to Twilight, and none of them are under any circumstance good things in terms of character. As we know, Amending Fences was the first solid episode to escape that pattern. And What about Discord and No Second Prances were not far behind, even though they had blame shifted to Discord at the very end of the former, and had Trixie kiss Twilight’s ass in the ending lines in the latter.
    
   Either way, I agree with @headlessrainbow, its a step in the right direction. Based on Twilight and Celestia’s behavior in the most recent episode, we might actually be getting close to a Celestia/Twilight episode where they confront Twilight’s need to obsessively please Celestia. Even though such an episode has not been announced yet, I look forward to the possibility. There is so much potential in the aftermath of the story once the characters are allowed to question almost anything in Equestria.