I never thought it was particularly dangerous, but I read that the fire department says it is and that it should not be done.
OTOH, the fire department does not recommend against driving a car or crossing the street despite the dangers in both of them.
My reading of your reply is that a hot plate is in the same danger category as driving or crossing the street and thus can be done routinely (with care – although how much care can be given while asleep?) But apparently the NYC Fire Commissioner disagrees with you.
Unless I have some facts wrong, which may be the case. I *only* raise this question so that we can understand the safety issues with a hot plate and/or blech.