There is a difference between copyright and trademark.
Those things or products that are created are allowed to be copyrighted.A person's legal name is not a product of creation.It's their identity.You
can't copyright personal names.See,legal names are the person's personal property.
However,it can be trademarked so that others don't use it.Almost all celebs do it to avoid others profiting from their names.And almost always,the artist has rights and share over it's use.A third party can hold rights over it only with the person's written consent.
It makes sense that they copyright the group's name,fandom name and other products as they've created all of them.But not the artists' legal names.
Besides,those you mentioned to go by original names have their two names fused,don't they?And their surnames are not frequently used as stage names.
So,I don't believe this.
Also,their stories are only lies.As if they would be allowed to choose rooms with rock-paper-scissors.What are they,eight?They are only appealing to fandom trying to be child-like(actually childish)
Everything is decided before hand.
About the street names' incident,it is more likely that bigshit didn't agree to it as it wanted to continue it's fantasy story of 'family not individuals'.
Besides,it won't earn any money through that naming.So,bigshit is least interested.
Just my opinion.