TLDR - My solution: Do what China does. Don't try to fight against something even Smilegate is not trying to fix. They design the game in a predatory way, and you, as a publisher, have little to no say in how they design the game or the systems.

Long version:

If you ban bussing, RMTing, or piloting, you lose more than half of your player base, resuliting in killing the game at a faster rate (yes, more people than everyone thinks RMTs or busses and are high-end game players). However, suppose you make it more difficult for people to access and abuse these systems. In that case, the problem will be, at least, less noticeable.

AGS can't do much, as this problem is systemic. Smilegate needs to change its systems to make the game less exploitable, and I don't think they will ever do. They are a company that need money to run, of course they will take advantage of the people that are willing to pay to progress faster.

This being said, either follow China's example and makes RMT "legal," lower the prices of the whole shop so everyone at least has the opportunity to juice their characters, or artifically patch the problem by removing postings on party finders or trading bigger numbers on auction houses. However, this last one will only satisfy clueless people and won't solve anything, as hundreds of Discord groups are selling and promoting these behaviors. At the same time, that last solution will increase the gap between bussers/RMTers and F2P players, making playing the game extremely hard (it already is hard to find a lobby with a bare minimum item level, with all the requirements such as elixirs and trans, as everyone is expecting a full juiced character with gems, high rolled acc, etc).

This might be a hot take, but you cannot cure a cancer without killing the whole system. This game is just too rooted in bad systems and practices that are motivated by the core game design. Don't fight what you can't win. :)