I think that not everyone can be completely focused all the time, especially with the example from the NFR. She lost focus for a second. That doesn't make her a terrible rider. If the girl couldn't ride, she wouldn't have gotten there in the first place. No one is born perfectly able to ride a horse, that doesn't make them a bad rider. A "Bad rider" IMHO would be someone who falls off but gets pissed and blames the world for it. I don't think anyone is a bad rider just because they fall off, then get back on with a cool head and push through it as a learning experience. That is not bad, nor is it wrong.
Edit: I just rambled so I added some fillers to link my words together better. Though I'm running off an energy drink and sour patch kids so bear with me.
You are free to disagree with me on this. I do not believe our differance in opinion is abnormal by any means.