Interesting reading - especially the conditions where you are NOT eligible for a DL medical. It looks like there are a number of conditions where a class 2 medical might be issued after additional investigation, but a DL medical would be denied.
My first impression is that it is more useful for a healthy person who wants to avoid the cost of a full medical, rather than for someone who loses their medical.
Can you give any examples where a person would qualify for a DL medical but not for a class 2 medical?