You should be able to work for more then just 1 faction 2 minimum, 3 Prefered. Working for only 1 is pointless as it removes all progress if you need some other type of gear from another faction.
Well, that is exactly why there are faction in the first place : to prevents you from accessing all the top gear at once and makes you grind.
They also made it available to gold payment regardless of the faction if you don’t mind paying for the game.
In the long run the goal is to grind all factions one after another so you can access to everything.