Yes it's a troll, and yes, the responses it gives are predictably ludicrous, but the question is actually a good one that can illicit good answers from/for others. Chiefly, there are people who need to get over their mythologized ideal of professional performing as being something other than a job.
It is a job. A union job that people are paid to do. And performers love what they do, as many people who have jobs love what they do, but they don't do it purely for love--no matter what A CHORUS LINE says. They do it for, among other things, a check and medical benefits. And so, like every other job, there is an expectation of consistent professionalism and a high standard for performance.
Like Henrik said, everyone has an off day. This is true of performers, of teachers, of office workers etc. but it should happen few and far between. If it is something that happens consistently, then there is a problem that needs to be addressed.
Performing may seem glamorous to some, but it's a job first and foremost. And a certain level is expected.
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body
