People said this about the Gorosei, Kaido and Big Mom too. I think y'all just forget that these characters can indeed dodge or block attacks, but purposefully choose not to because they know they either won't be hurt or the damage won't be permanent anyway.
That especially fits the HKs due to them being pompous, rich assholes. Of course they'd take all these blows head on without defending whatsoever, it's a great way to flex superiority.
When they ARE forced to block blows, we see that they actually can do it, as seen with Sommers and Gaban. They just typically don't bother to