One of the myths around radio regulations is that “in an emergency, nobody needs to worry about licensing.”
It’s not true. Every class of license has rules that specify what may be done in the event of an actual emergency. For GMRS, the rule regarding emergencies says that in an emergency a license holder may allow anyone to operate his or her station.
The difference is subtle (and perhaps pedantic) but is not the same as saying that anything goes, nor should it be. Having a bunch of people who know nothing about GMRS (or any other service) suddenly start using the service, without knowing anything about the channels, the limitations, and the capabilities, will only serve as an impediment to effective communication.