The campfire scene gets its name from stories in which people on a journey stop for a meal and have nothing to do but talk. Campfire scenes reveal character, both to the audience and to the other characters. They give the members of a new team a chance to bond. They make us believe a story is about individuals rather than archetypes. The campfire scene is to a story about a team what the falling in love scene is to a romance: it makes us want to see the characters succeed.
Rogue One would've been much better with a campfire scene. There might be one on the cutting room floor—one character calls another "little sister", which only makes sense if they'd had time to form a bond. There were plenty of opportunities for campfire scenes—a story can have many—and yet the few attempts did nothing to convince me that any of the team members came to care for anyone they had not already cared for, except the guy in charge of the mission, who apparently liked the hero because she was of the desired sex and reasonably competent.