Foodstagram vs. Chefs

In the era of social networks and food blogging, where we are now used to sharing details of our everyday life with online communities like facebook, instagram, foursquare, etc., how would a foodie feel if s/he were told that s/he can't photograph his/her plate in a restaurant?

It is news of these days, both in New York City and Milan, that some chefs are forbidding their clients to take pictures of their food in their restaurants.
What are they afraid of? They say it's because they don't want to disturb the atmosphere of the restaurant with the flashes and that people standing up to take the pictures distract the other clients... c'mon... I've never stood up to take a picture in a restaurant and a flash would be the thing that would bother me less (what bothers me is other clients' loud voices but they don't do anything about it).
Why don't they realize that if a client is taking a picture of their dish it means that they appreciate its appearance, and they could even learn from that, to make their dishes nicer, and (since we're there) their portions a bit bigger...