It seems like she got famous for being a cute girl and a gamer, and doing videos showing herself playing video games, and then doing commentary on video games. Video gamers tend to be male, nerdy, and, let's say they react in a very predictable way to the presence of a cute girl. She doesn't always use that voice. Here she is reporting on a video game convention, and if you can't imagine what all those nerdy gamers see in a girl who looks like this in a dress like this well...
https://www.youtube.com/watch?v=g5t4YXu9V2I&index=100&list=PLa7SaB6RofYQJqrFPqniKN4LkYJSseg34&t=135s