OK, atleast you need CoC to be able to destroy the heart. So not every random strong attack can destroy it.
But the Roger Pirates cutting them up many times and not once to hit their heart is absolutely ridiculous...
And how the fuck didn't Luffy's attack kill Sommers? He was torn to shreds and you can clearly see black lightning...
Also, since destroying their heart is now their goal, that means that Sommers and KH are actualy gonna die. Which is crazy considering the SH's never kill.