You can do Persona Play very happily, forever, and never bother to join a Guild. Guilds are not for everyone. Outside of the Dragonlands RP area, Furcadia doesn't enforce any play style or in-character player claims. The truth is that players are free to say they are anything they please unless they voluntarily choose to be a part of a group with rules to control it.

We have Chartered Guilds because some players want more than just chaotic "Let's pretend."

They want their character to be able to grow, by learning new skills, for example. They want their character to be able to affect the game world in a way that feels "valid". Most of all, they want the game world to make sense. The Guild Charter establishes what does and does not exist in that Guild's Continuity. The leader of a Chartered Guild has the option to maintain character sheets, award some form of advancement, etc.