Duh! I thought da capo was da head honcho in da Mafia.
As both a singer and a guitar, bouzouki and mandolin player, I've found the capo- in my case the Shubb- useful for adjusting to another singer's legitimate requirement for a better pitch. Since I use alternate tunings which need open strings, I find the capo preferable to bar chords. I do, however use the bar option for more funky rock, jazz or boogie type of arrangements. I guess flexibility is part of musicianship for me. I capo or not according to the needs of the song or tune.
I note a significant difference between the attitudes of instrumentalists and singers. Those who do not sing find the demands of those who use their throats frustrating. I have a beloved friend who is completely mystified by the requirements of instrumentalists, great singer though she is. The capo is a good, simple device for easing your way round such relational complications.