Basically this.
I was a gymnast for 18 years (from 2 - 20 years old). Obviously, it wasn't professional level the entire time, but starting a bit before high school, workouts would be 5 or 6 times a week, for 4-5 hours. There was never any weightlifting, only body weight exercises. Those guys you see on TV doing Still Rings, Pommel Horse, etc., they didn't get that strong through weight training. It's just hours and hours of practice and so-called 'endurance' conditioning. I say 'so-called endurance' because most gymnasts that I met were pretty bad endurance wise, judging on ability to run for awhile. A lot of us topped out at a couple of miles, before we needed to walk.
Gymnastics is a sport that isn't assisted by weight training. There are a few exercises that use weights, like wrist therapy using 5-10 pound free weights. But all those physiques you see on TV are just thousands of hours of work, and those hours make for some of the leanest, strongest people.
Here are two videos of some good, professional-level routines:
https://www.youtube.com/watch?v=ScgJJDYeqqg
https://www.youtube.com/watch?v=qRDzQX6MzHo
You literally can not learn to do that through weightlifting. You cannot gain the strength those two use through weightlifting. It's not because the positions themselves are difficult, those are usually the easy parts to train and practice. It's the transitions between two different positions that is difficult, and cannot be trained by weightlifting. Gymnastics is a dynamic sport, weightlifting is a static exercise. The best that weightlifting can do is make the holds a bit easier, but that isn't really necessary, because those aren't as hard to train as the fluid transitions.