A Chamber of Commerce was self-explanatory to everyone seated at Braum Tavern.
To join one was essentially sharing their resources and doing in-trading without going through other channels.
Of course, that didn't mean one would be restricted to one's chamber of commerce. But it was an unspoken rule to only be more active and loyal to one specific chamber of commerce.
Think of it as buying groceries and becoming a member of one supermarket.
Although one could always get more memberships from other supermarkets, nobody would have the time to browse through all the supermarkets and would usually only have one main supermarket.
And everyone seated at Braum Tavern knew about the Vanguard Guild's displeasure with Miracle Pavilion.
