Shouting call your hits doesn't solve anything, nor does it make the game any more enjoyable. Though I admit that I've shouted this in anger a few times.
Once I spent two minutes shooting this guy's butt. Must have seen ~20 rounds bounced off it. He never called his hits, but just flinch back into cover, and a few seconds later he would present his derriere to me again, like it was mocking me. I got a bit angry, so instead of shouting call your hits, I moved out of cover and ran towards him (and the opposite team) and shot his ass point blank, and made sure he was out for good. Of course I got lit up by his team.