And yet other large scale MMOs don't have this problem or at least, not the the degree where it harms the quality of the game.

Fact is, Square are not putting nearly as much effort as they should into combating this. Every single RMT I've seen is level 1, stands in one spot, occasionally jumps, and I guess they either walk or teleport. I may have encountered one that teleported while I wasn't looking. They stick around in the city states and spam messages. It should be ridiculously easy to ban for this activity. No real player behaves like this.

Since they won't do anything to fix this, at least give us proper tools to hide these messages. Or even better, so not to make us write down phrases or some crap, allow Guildwork to be installed. I hear it works, but I'd rather not get banned for trying to play the game without being harassed.