I've heard of Snobol, but I'm totally unfamiliar with it.

It's not as if you actually filter anything with the cycle - it just sets indicators (boolean values) depending on whether a value changes or not. It doesn't actually retain breaking (or broken) values unless you do it explicitly. There are conditioned sections of the program that are run/used according to what point in the cycle you are in. Multiple levels of level breaks make the thing damned useful.

I guess it's just that the cycle makes programming in RPG easy. I'd probably totally hate the language if I had to write RPG code without it.

Without the cycle, RPG is just... Lame.