Question on a power build in Champions Powers

[Stone]

On page 75, there is a "sticky" darkness field built as follows:

Darkness 3m
Usable as an attack +1 1/4
Range +1/2
Defense is Darkness or Light powers

My questions is since Darkness already has range (10x base cost, H6E1 pg 186), why is the range advantage needed for this build?

[Steve Long]

Because Usable As Attack powers by default have No Range, even if the power they're applied to ordinarily works at Range.