How so? There is a stark difference between incrementally moving in the right direction, and incrementally moving in the wrong direction. Climbing up a rope one inch at a time, and sliding down a rope one inch at a time can both be classified as "incremental" movement.
In the example, the NRA is incrementally making movements towards a pro-gun America, where as voting the lesser of two evils is incrementally moving towards an anti-gun America.
"There are no finger prints under water."