Throw-in violations

[just another ref]

In another recent thread there was a question about a throw-in violation, which caused me to review the rule and case books on this subject. As in other rules, the case book adds things which could not be determined from the rule alone. First, if the thrower steps inbounds with either foot, it's a violation. Everyone knows that. But why? The thrower shall not carry the ball onto the court? Thrower is standing out of bounds and touches inbounds with one foot. I wouldn't have considered this carrying the ball onto the court. But, this one takes it even further: 9.2.5 says that if thrower A1 reaches out and touches B1 it is a violation because touching the player gives A1 inbounds status.


Huh?