The Lydian Dominant Scale

I got excited when I learned about the Lydian dominant scale:

1 2 3 #4 5 6 ♭7

and could sing it without much effort on the first try. I seem to be getting better at this sort of thing!

More importantly, it’s a really cool scale. Rob van Hal’s video explains what it sounds like and what you can do with it:

You can think of it as a blend of the Lydian mode, with its mystical raised 4th:

1 2 3 #4 5 6 7

and the Mixolydian, with its lowered 7th:

1 2 3 4 5 6 ♭7

But why does this image from van ...