Ookami-kun said:
See, my problem is that somehow everything happened because of her, especially in CMC. That thing really bothered me (especially with its "lesson" that somehow everything is connected).
CMC was unbalanced, having
everyone's cutie mark reveal being the result of Dash's cutie mark reveal, but it was kind of required, since any unifying force would have to be flashy, and if you want flashy it has to be either Twilight or Dash. And it's kind of predictable to have Twilight, the protagonist, be the link. And Dash's reveal was already known to the audience. Her reveal would have been a weak point if it wasn't beefed up somehow.
Also, Dash didn't really "give" anyone their cutie marks. They were all at a point where things were about to happen, and Dash's showy display was just enough of a nudge needed to push things in the right direction. Applejack for example was regretting her path in life, staring towards home, crying even, when she saw a line pointing home and said "Fuck it, I'm going home." Having Dash's show be "the trigger" for events doesn't cheapen anything. AJ could have seen that line and said "Home? No way. I'm not giving up yet. Do you hear me universe?! You can't beat me so easily!" She could've done the complete opposite of what she did. The interpretation of Dash's display was all Applejack.
Oh and you can be imperfect and still a Sue.
The theory is that interesting characters have flaws. A Mary Sue is supposed to be perfect. Her "flaws", if she has any, are supposed to be things designed to cause more attraction than if she was merely perfect. Fluttershy's shyness is a good example of that type of "flaw".
Of course, a good character
doesn't always need to have flaws, and "attractive flaws" are not necessarily a bad thing.