Have you seen the Blues Brothers movie? There's a certain country gig where the band is behind a wire cage....the reason? The audience keeps chucking things at the band if they don't like the song being played.
I see the forum being like this. There are certain posters who think themselves to be critics to the point of attacking, mocking or whatever they can do to diminish the truth of it. A little like the Wild West. I guess it entertains to some degree. Anyway, the movie is quite entertaining.
side note: I remember gigs in my younger days that were similar to those scenes!