I wonder how many people have read this

These agile fighters pride themselves on their skills with knives and daggers to make quick work of enemies.

Lurking in the shadows, adhering to no laws but their own, they punish the wicked, pilfering their ill-gotten gains and delivering them to the downtrodden masses. Thought by many to be mere common criminals, some would say they play an unseen hand in maintaining order in the buccaneer's haven of Limsa Lominsa.
^ From the lodestone.

This class is thief, with another name. There's no ifs or buts about it. It's thief. With a different name. Now that we've got that out of the way...

Yes, jobs don't have guilds. But rogue IS thief. The jobs are NOT the same thing as the class. They're similar but they are, lorewise, something different. Thief job would be the same thing as rogue, with the exception that they would probably be booted out of their rogue guild because there's a reason they're called ROGUE not THIEF.

Finally, no thief please. I hope they never add it now. I said previously maybe in a diff thread, I prefer the aesthetics of thief over ninja, but thief would add nothing special to gameplay and would be the same role as ninja. It will be a dps with 5 different dps abilities. I really would prefer they use it's 2nd job as something entirely different.