Journalism as Sociology as a Social Science

There's a trend in journalism which I've noticed in the past couple years. I think it's becoming more and more common all the time, but it baffles me because I don't understand it's value.

When reporters cover public events, like parades, dances, and so on, they have a tendency to join the demonstration. They would walk in the parade, or paint their faces, or do something which shows them participating in what they're reporting about.

My question is, how is this helpful for the audience to understand what is going on? How does this help represent the truth? For one, the reporter is most probably not as skilled in whatever the demonstrators are doing, and certainly won't have a background of working with that group. So the reporter is not representative of the events. It seems to me that showing someone from the event being interviewed, and hearing about the event from them, is more productive and useful than seeing the reporter do stuff.

This actually reminds me of what I learned about social interactionism, and how sociologists have to immerse themselves in the culture they're studying. Another question arise, this one more dire than the previous: how does the sociologist remain objective if one is to be part of the culture? It seems to me like the whole religion thing: Believe, and I will show you proof. This seems to be against how science is done.

The above ideas are all poorly written, but I really am puzzled by this.