While reading Levine talk about the rules being imposed on the arts in the 19th century, particularly the rule about clapping between movements of a piece, I couldn't help but think of the Facebook groups called something like "I don't clap between movements." The existence of such "groups" (it's not so much an organized group as a bunch of people attributing a quality to themselves) shows that these rules are both still securely in place and still quite often broken.
There is most certainly an elitist air about the profiles describing the groups, an assumption that those who are not members have no place attending concerts in the first place. On the surface it might seem like a way to educate the ignorant, but of course those people would never even think to look at such a site. Really, it's a way for an insular group to feel superior and broadcast that superiority. I would be very surprised if there isn't someone in the class who's a member. This is not an attack on you. In fact, I don't like it when people don't follow these rules either. These are just my observations.
And who hasn't been to a concert where this particular rule isn't broken? It especially happens at student concerts, when someone's non-musical friend or parent gets excited over seeing their friend/child do something interesting. So I ask, should we stop inviting our friends to our concerts if they haven't been acclimated to the rules?