These were suggested to me at a recent conference as a synonym for what I was calling a Dead Zone, with some kind of public icon on the entrance.
You will avail yourself of such spaces when you want to frustrate cell phone and computer use, radio reception. People may still have personal listening devices. The point is to have conversations, meetings, without the interruptions or distractions of telecommunications.
People entering such a room are signalling their mutual willingness to suspend contact with the outside world and just focus on the matter at hand. One might pull out a cell phone to remember a name, but by social convention this might seem gauche.
You might even have a locker system like in a gym, although that adds a layer of inconvenience.
Some people simply do not wish to part with their telecommunications devices, especially if not that familiar with an establishment.
The "check your phone at the door" policy need not not involve physically parting with your device, although you may wish to park it elsewhere, as a convenience, when heading into a Faraday Room for a long day of intimate discussions.
Having stories to take home, about some of the Hogwarts-like qualities of the place (inexplicable magic, it might seem to some) is what any good casino aims to provide, whether or not it permits gambling.