Something like this could actually be really fun if done right. Companions not in the active party could act as a 'reserve party' of sorts that keeps the camp tidy while the main party is gone. There could be unique scenarios like welcoming Scratch or the mysterious skeleton to the camp.
One could take it a step further and have characters get their own playable solo arcs while they're back at the camp, like Astarion trying to hunt on his own and accidentally getting himself trapped in a perilous location with tons of running water around him while also trying to hide his tracks from whoever is hunting him. Or Lae'zel trying to ask random passerby for the location of her creche/trying to get them to ferry a message to her own people, only to fail miserably due to her obvious intimidation factor. Such a concept would also heavily encourage rotating the party.
Come to think of it, I cannot remember a single game in existence that has attempted anything similar to this.