One of the most creative artists of the rock and roll era, although she was on the folk end of the spectrum.
If music hadn’t existed before her, Joni Mitchell would have invented it all by herself.
Joni also used alternate tunings on her guitar. Trying to figure out her guitar tunings is a nightmare as she is all over the place with them. I don’t think she ever used standard tuning. Many other artists followed her leads with the alternate tunings, Stephen Stills one of them.