The start value of her routines are absolutely ridiculous. She lands all of her tricks without so much as a hop on the landing. I remember when Nadia Comaneci had a perfect 10 way back in the day. Now these girls are getting 16 and above. Simone Biles does tricks that the men can't even do. It's amazing to watch.
Look at all of Simone Bile's world championships. All of her titles, and her scores compared to the rest of the global gymnastics pool of candidates. She has achieved almost the current equivalent of 10s. She and her teammates crushed the competition in Rio and won by a huge margin. She can certainly be called the best ever.
Simone Biles has one more medals than any other gymnast, and not simply because there are more catagories than in the past. She has dominated because her strength, training, and hard work have made her the best gymnast to walk the earth. She could easy best any gymnast past or present.
While it is true that Simone biles has remarkable talent, it is impossible to term her (or any athlete for that matter) the 'greatest' ever to compete in her sport. Further, greatness is not only about one's prowess in a sport, but also about how they hold themselves and if they respect opponents.