Does the ToS say you have to respond to /tell? Can my paid for accounts be banned because I don't respond to /tell?
Yes, like Jumbur said, they are farming plat. They fill up with trash loot (diamonds etc.) and warp to the vendors in the zone to sell, then repeat. On my live server, there were always half a dozen groups doing the same thing in Dead Hills, in the valley that goes up to Tower of Rot. They were there 24/7/365 for about 10 years with no consequences. They are probably still there. If only there was a way to log activity like this on the server.
I have a suspicion that ingame platsinks are tuned along the average plat acquisition, and that those plat-farmers seriously screw up dbg's statistical analysis they use for tuning. I have serious trouble keeping up with all the platsinks. I blame the inflation on bots...