User blog comment:FairyRaven/Fairy Tail Chapter 408: The Definitive Demon, Review and Commentary/@comment-24277053-20141110135803/@comment-7418318-20141111095253

I meant that Erza is defying logic and even the rules established for the world of Fairy Tail itself so much that we can't go and say "Erza could do it, so everyone else can do it too".

She's a rule-breaker, so we can't deduce rules from watching what she did.

And I have no problem at all with Lucy and Cana's learning process either, quite the contrary. I like that they have to learn to use their spells properly and I'd prefer if it was the same for everyone else. I'm fine with the occasional exception, if that exception makes sense, like Hibiki giving her knowledge for example.