A Serious Question For Riot

The Question: What about Fiora's kit makes her healthy?

It's a sincere question. From my experience, as well as watching others, she can start out very poorly and excel easily after making bad decisions and poor playmaking. If you out build her in Attack Damage, Magic Damage, Armor, Magic Resist, Health, Speed, Critical, or anything you can possibly do to her, She will slice you in half and eat your gizzards. Now from a logical standpoint, that doesn't sound the slight bit healthy, or really skillful to do.. You may disagree with me, but her passive alone does a ton of things I wish I could do lol. I don't fancy her in the slightest. I would never play her. She seems to be a skill-less champ more than a skillful champ.

Now I'm saying this from a point of view that I did not have trouble with her. She isn't necessarily a problem for me. My problem is, she can out sustain a champ that has better everything than her, and if she doesn't kill them, she puts em out of the fight. Nowhere, logically, does this fit as a healthy mechanic. If there is some hidden reasoning, I would love for a Riot Member to respond to this. I know it sounds cliche, but if they don't answer, I'm assuming they don't have a legit reasoning for this kit on Fiora. No offense met. Just the only real explanation.

I am coming at this from a completely analytical standpoint. I'm trying to be as unbiased as one can be. A logical explanation would greatly set me at ease. Thank you for your time.

Edit: This is not a demand for a nerf or anything like that. It's a petition for a logical explanation to why she is the way she is. If she is healthy and there isn't anything wrong with her, it should be very easy for Riot to respond with such information.