This is a walk though area only

Went to a dance recently held at a school. In the corridor there were A-boards with a curious sign:

A further sign explained that that the corridor wasn't to be used as a social area. Now, I could understand the need for a prohibition like this in a narrow corridor that was getting blocked but this one was about 20 feet wide and hardly anyone was there. I even wondered if the signs were intended for use elsewhere and were misplaced but this wasn't so - this second very poor photo (I only had a very basic camera phone with me) shows a sign that includes an image of the relevant corridor:

 

It does seem to me to be a bit over the top on social control. Turning to Google, I found an Australian school that has a similar idea in its canteen