Handicaps, defects, we tend to interpret them as problems, as something that's wrong. A surprising number of times, what you would see as a defect is actually an indication of hyperfunction rather than subfunction. That is, the things we perceive as defects, actually make people more functional or come from a place where they are more functional.
This understanding matters, because in teaching you will come across a lot of people with handicaps, with problems and dysfunctions, You can show them that these problems are not there because they are less than others, but instead because in some area, they have something more. It especially matters because those who are called to be something impressive, are those most likely to have a dysfunction. People who want to change the world, very often have a disadvantage at first. They will say, "I always wanted this thing, but ... I can't read, I can't walk, I don't know how to do this thing ... "
You can find an example in the book "The gift of dyslexia", that describes how people who have problems with reading actually are extremely gifted at spatial rotation and hyperlinking - signs of moving from a words to a visual-spatial way of processing. They have something more, but as a result they are experiencing difficulty fitting into a more traditional linear, verbal world. Something similar goes for people with a stutter, who so very much want to say so very much, and think so fast that the verbal expression just keeps falling short about what their brain is trying to do.
These handicaps are amazing gifts, but they take more practice to train and more work to tame than the smaller and more common abilities.