The answer is no. In fact, the largest smashers have already exceeded the point where their strike is more powerful than their armor. The power of the strike increase roughly in proportion to the cross-sectional area of the muscles in the merus. The armor increseas in rough proportion to the thickness. As you scale up, the power of the strike increases much more rapidly than the strength of the armor to withstand it. This is probably one reason that O. scyllarus are so brightly colored and rarely escalate their fights to all out striking.
Roy