You're probably correct in that some weights are involved, especially for those gymnasts who compete.
I know one thing...doing 4 sets of 4 exercises on the rings, pullups, dips, inverted bodyrows and pushups pumps my upper body like nothing else.
My mid to lower forearms take a huge beating on the dips and pushups because of the stabilization required on those movements using rings. I only started using the rings last week, so it will be some time before my stabilizer muscles are up to snuff.
But there's no rush. I'll get there by being consistent, and I like the challenge and the opportunity to improve myself in different areas. Keeps things fresh.
There's a ton of movements that you can do on the rings. I'm just trying to build some strength on them with basic movements before I try to move on to more advanced movements.
Insert profound martial arts quotes or tough guy phrases here.