To make it more even and more of a challenge. If we had 1-39 & 40+, people would simply pick 1-39 most of the time, whereas a margin of 24 points makes you think a bit more.

It's also a better comparison to the Union & League margin of 1-12 & 13+ points. If you look at the odds, in most games 40+ is quite a bit longer in the betting than 1-39 points, whereas in League & Union, the two margins are reasonably close together in the betting.