Quote Exalted Wombat:
his job is to play at an appropriate volume so as to accompany the choir rather than overwhelm it.
Out of curiosity, is it possible to play a pipe organ in a church louder or quieter? I presumed that the keys act more like switches to the pipes and do not respond to velocity, but I've never played one, so I have no idea.
This indicates that there should be a volume pedal, but in the case he mentions, doesn't affect all the stops.