Do some things cross a line? Sure.
However, the mental game is just as much a part of the athletic competition as anything. Participation in jawing, gestures, pushing are all designed to either get your own head in the game or get into your opponents head. The less your opponent is focused on the game and is distracted by what you’re saying or doing, the more of an advantage you have. The trick is to be able to do it as part of your own game so that your own efforts aren’t a distraction to yourself or teammates.
All of the greats in every sport are blessed not only with exceptional athletic ability and skill, but also a mental edge which included jawing, trash talking and other forms of psychological warfare