With the bluegrass bands that I played in over the years we would arrange set lists around capo placement so as to minimize the need for retuning on stage. And, FWIW, and for example, Tony Rice who is IMO on of the most remarkable guitarists in the solar system uses a capo when playing bluegrass. The structure of bluegrass requires certain runs and conventions on the guitar that would sound really odd if not played out of certain chord positions via capo use.