Well, I'm glad we agree on something. Remember that The Hop fest has taken many years to grow, and it's not so good if it pisses with rain, but thats only happened a couple of times to my knowledge. and it looks like they've got good weather this weekend too.
But the only way to do it is by having a hard core of enthusiasts ,with the suitable skills. You still have to hire staging, PA, crowd barriers, St Johns ambulance. You have to get permission to shut off the streets so negotiations with the police are mandatory. One person couldn't just turn up and do it on a Saturday afternoon. The Hop has a committee who spend several months organising it. And it works.