Really? That was always the rule when I played in HS and college.
I don't know about high school, but you are correct about the NCAA rules.
The on-line MLB rulebook still has the old rule.
8.02Official Rules | MLB.com: Official info
The pitcher shall not --
(a) (1) Bring his pitching hand in contact with his mouth or lips while in the 18 foot circle surrounding the pitching rubber. EXCEPTION: Provided it is agreed to by both managers, the umpire prior to the start of a game played in cold weather, may permit the pitcher to blow on his hand.
The NCAA rule allows the pitcher to go to his mouth on the mound, but not in contact with the rubber, and requires the wipe. Unfortunately, the NCAA site changed on March 10, and since then you have to go through a shopping cart to get a FREE look at the rules, so I can't provide a direct link, only a link to the shopping area. NCAA Rules
The equivalent NCAA rule is 9.2(d).
JJ used to go to his mouth off the mound, and then rub down the ball, especially early in the season when the humidity is so low down here during our dry season (30% is common March & April).