Correct me if I'm wrong, but I think Atmasphere is referring to system synergy; you can get the sound you seek by well matched components in your system.
Actually, I'm not talking about synergy although that can play a role. I am simply stating that a speaker is 'ideal for rock' as opposed to other forms of music is one of the biggest myths in the speaker world.
If its good for classical and jazz it should be good for rock. If not, the speaker has a serious flaw and likely isn't all that good for classical or jazz either.