Wow... I'm not listening? Yet you pick only a single point in a long list of problems I saw in her back story to disprove all my points. Then bring up irrelevant points to support your hammering of a single point I made. I'm sorry but that is a strawman argument.
To be clear it was the accumulation of problems and weak back story that gave me pause, plus Hiro's history with Fairy Tail of doing exactly what happened with Kagura with other antagonists, only to 5 seconds later have Erza beat up said antagonist right after hyping them up to the heavens themselves.
If it makes you feel better, sure any joe could be strong if their parents where weak... but that doesn't prove it so either. I'm just looking at the accumulation of facts about her history and saying it still a bit pushing it since too many unlikely events need to be thrown in unles either Erza is holding back, or Kagura is getting a power up. Occum's razor is what my argument is going by, so I fully admit its not proof but imho just more likely. Take that as you will but I'm willing to bet you'll just read what I posted, still disagree, then rage if Kagura loses to Erza in the near future.
And Sabertooth isn't the stongest guild in Fiore, they're losing by a single point atm