No, I am not. Your ability at anything is just by-product of the functioning of your brain.
imagine that there was a room. and in this room was an exam paper. one by one people came along and attempted to answer it...most of the time people could spend all of their allowed time focussing on the question, but whenever a dyslexic person came along, a padlock was put on the door and they were told that they had to pick the lock before they could start on the question.
once they have broken through the lock, they are just as capable as everybody else, but they have had extra work to do.
now, about the maths thing. you cannot compare maths to an essay based subject. Maths is a skill/ability , essay based subjects are not.