“Supergroup” feels like one of the most loaded terms in music. It’s a statement of fact, but one which carries a potent subtext of inevitable creative differences and clashing egos, underwhelming output and bitter recriminations – in a word, disharmony. But boygenius, the collaboration between Julien Baker, Phoebe Bridgers and Lucy Dacus, is the very definition of harmony and respect, a united front against the concept of “women with guitars” as a genre.