No one would watch average joe's average airsoft games.
Youtubers create controversial content on purpose. Look at this thread, we are talking about a video, that's exactly what they are going for. They are not like that in real life, the audience, you form them to what you want to see. So I think it's not the youtubers who influence the players to be like that, it's the other way around.
Mustang moves crosshairs to the head, chooses titles and thumbnails that can be triggering, etc because that's what people want. Even the ones hating him. He's very good at creating good content from normal game days.