[theboys]

This is an interpretation designed to make a referee's job more difficult. I mean, imagine yourself explaining this to an uninformed howler during a hotly contested game.

Ref: Tweet! (You make the block signal.)
Coach: How can you call that a block? The kid was standing perfectly still! The guy ran over him! Look, he has steamroller marks on his chest!
Ref: Sorry, Coach. His foot was on the baseline.
Coach: (Confused look, since he doesn't know the rule. Shakes his head. Walks away.)

Coaches regularly teach kids to cut off the base line, which probably means kids regularly step on the OB line while doing so.

As for having a kid look down to make sure they have a legal spot on the court, that just ensures the kid will be positioned to quickly look up as the ball handler goes by for an uncontested basket.

So, if your association meets with coaches before the season to go over rules, you better highlight this one.