If you aren’t positive that the run-selling is RMT, then the player really hasn’t done anything wrong.

It’s like anything else in the game- a player has put in the time to be able to sell a product that has some kind of demand. Another player doesn’t want to put in the effort to do it themselves, but has the means to pay for the service.

It’s essentially the same as paying a crafter for their products.

Moreover, if some kind of content built for 8 people can be done with 7, perhaps the content isn’t really that difficult -or- the 7 man team has earned some kind of right to “sell” their skills.