Promo Trolls -_- WHY can they see your promos and care

Greetings, I have been watching some streamers to help me learn things and styles of league play. But one thing that I see is that some players when in their promos their own teammates will troll so the person loses their promos. In the twitch chat I brought up the idea of not allowing people to see that you are in your promos so they will not troll. Plus if they still troll you they can be banned fast.