If pilots are really busy, performing some actions, they can just ignore my message
Somebody hassling you in your ear is a distraction, irrespective of whether or not they make the
decision - hint: added task - to ignore you.
The equivalent is transmitting on a new frequency without listening out beforehand. I'm sure you would get pretty hacked off if we all did that, wouldn't you?
Edit: Didn't see mad_jock's post... beat me to it.