This right here. You cant have fomo for a system that already prevents you from playing if you are not paying.
Saying that the trading post is fomo is like trying to say raids are fomo. You are not paying some extra amount to play the game, you are not offered a standard sub, then a premium sub that gives you access to things a standard sub does not.
You are either playing the game, or you are not playing it the trading post does not create some random FOMO out of nothing.