Why do they do this?

[Dan_ref]

I have found that maybe the most misunderstood rule might be what a player can and cannot do on a throw-in. Tonight during a dead ball I had a conversation with a coach concerning this:

"Hey, is he allowed to dribble the ball as he runs the line on the throw-in?"
"Well, yeah, since it was after a made basket he can run and dribble."
"WHAT? HE CAN? I've never seen that before!!"

Almost always at this point the coach's voice, and his eyebrows, go up. Sort of like I just told him he's not gonna be getting his mug of hot chocolate before beddy-bye tonight. Anyway, to continue this conversation:

"Well coach, he can pass the ball to a team mate, right?
"Yeah, but a dribble is a self pass and that aint allowed."
"Coach, I'll be glad to show you the rules later, if you like."
"Never mind, I trust you."

Sigh. And it's not like this is a first year junior high coach, this guy has been doing this forever and has gone to the state tourney a number of times.