Joni Mitchell made an interesting observation in an interview.
She was talking about Bob Dylan. She said the brilliant move Dylan made was using a fake name/fake identify. HIs real name is Robert Zimmerman and Bob Dylan is essentially a character he created.
She said the reason it was so brilliant is because being a singer-songwriter means you burn through your personal stories eventually and then there's just nothing left to plumb.
Dylan, meanwhile, is a fictitious character and so through that Zimmerman is free to endlessly create anything he wants.
I'm not exactly sure if I agree with her but I've thought about it a lot and I think there may be something to it.
Obviously that's music not writing, but I think in general it's the same principle you're bringing up.