It seems to me amateurs have enough trouble getting the ball in the catcher's mitt properly let alone attempting to precisely "hit" someone in a "spot" where they won't be injured. What young ballplayer can be expected to carry out that order with perfection?
What if you throw at a kid's hip and while he attempts to get out of the way of the pitch, he tears his ACL or some other ligament in his body? Are some messages worth that kind of damage? What if attempting to hit a kid, you miss and hit him in the face? Would that message be worth it?
I submit this is a potential criminal activity. Order a kid to intentionally hit someone, the kid misses and does some real damage, and the person who ordered it could go to jail for criminal assault. It all sounds harmless enough in theory to "send a message" but it perhaps might be the most irresponsible thing an adult can do imho - no matter how much someone might deserve it.
For young pitchers out there reading this thread, you must refuse to follow this instruction imho - even if it means the coach will punish you for it.
Someone could get seriously injured (or worse) where you might not ever be able to forgive yourself if you cause that kind of damage. It would be better to walk away from the game imho than to potentially seriously injure someone by "sending a message."
Accidents and injuries will always be part of the game but that is the domain they should remain - as acceptable risks that are part of the game. I understand the need for pitchers to back a kid off the plate and sometimes the kid might get plunked because of it. That is far different in my mind than intentionally trying to hit someone.
Perhaps I am in the minority on this one and there isn't much difference from "backing a kid off the plate" and "sending a message"