4th job Single Target DPS

Then why include a calculation for Marksmen not using Snipe?

Blaze doesn't have the *greatest* of range, Killing Wings does. Some people could use Killing Wings over Blaze for that reason, and if your going to Include Phantom Imprint and Illusion Spam in the dps calculations, there is no reason for Killing Wing not to be used either.

Also a question, would using Final Blow for Arans in 1v1 hinder their dps in the end?

Because Snipe's damage can't be accurately determined even at level 200 due to its wacky cooldown. The Snipe box only shows how much a Markman's damage can potentially be boosted by perfect timing of Snipe.