I agree with this. Another good example is Chuck Liddell. While he does train grappling, I'd say he's more a striker, but yet, hes got a great takedown defense.
I've heard unconfimed reports from his camp before his Couture fights that Liddell spends more time traing his takedown defense and groundwork to get up then he does on his striking. His wrestling credentials outside of MMA are actually stronger than his striking ones, although clearly he is quite good at both.