I didn't know it ever was...when was that?
Apparently tho it still COULD be...but never is.
"Once an official spots an offensive holding penalty, this will result in a 10-yard penalty, or half a distance to the goal line if the line of scrimmage is less than 20 yards from the offense’s end zone. However, it could be bumped up to a 15-yard penalty if the refs deem the blocker’s excessive aggression."