"Held back" by what, exactly? RBY's OU tier is plenty balanced enough. A tier only needs to be balanced to the point of being reasonably competitive and skill-based (and, of course, simply "fun"). Any other bans are unnecessary disturbances of stability, and should just be used as gimmicks or for establishing a whole new tier of play.
If RBY does need a shake-up, it's through banning the Normals more than through anything else. The Rocks don't really dictate anything about the metagame, except by strengthening Eggy (who's godlike even without the Rocks) to nigh-mandatory status. Most of the time, rocks are used in reaction to other major players, most notably Snorlax and Zapdos.