Is it because they're bitter and disappointed at not being good enough to conduct Ex Cathedra or the Sixteen?
Seething after being read a lecture on the importance of the final rehearsal, on a day when I got up and drove 30 miles to get to choir in fog and rain, after 2 days in bed with a chest infection.
Endlessly demanding, childishly rude, jaw-droppingly inconsiderate - and that's the better ones.
I suppose if they had the people skills as well as the musicianship they would be conducting Ex Cathedra or similar.
Ah well.