I find the problems caused by RMT grossly over exaggerated.
Did I see gil sellers in XI?
Yes, plenty of 'em but they didn't harm my enjoyment of the game in a significant way.
What DOES however harm my gameplay experience in XIV in a great way is the lack of an AH.
And still I see gil sellers in-game.
I'm not tempted to buy gil as I'm swimming in it. Just nothing to use it for.
I am purely speculating of course. My first MMO was XI and my second was XIV so I admit to a lack of experience with the topic. At the same time, I "did see" a lot of issues with RMT.
Are they game breaking? NO. Could they be? POSSIBLY. Do I care really? NO.
My point is, RMT "can" mess the game up because, when you have very active RMT on a server, they mess with prices to deter people from monopolizing on crafts. The problem with this is, since these guys have a dedicated mission to make in-game money, they use tactics to control the value of items they sell. They make it so it is hard (not worth it) for people to level their crafts because there is too much of a loss to do it. They make it so low level crafts bottleneck. I mean, actual players do it too but they do it because they are stupid. I have seen RMT intentionally destroy a market. I have seen it a lot.
I guess a good counter argument is, I have also seen RMT add to the game. In the same way they mess up pricing to achieve total domination, I have seen RMT provide stability to a market. I have seen them make HQ gear prices realistic (by lowering the cost across the server).
I think the lack of an AH would be fine (even better) if they game was designed to support the lack of one. If everyone was required to kill mobs all over the world, at their respective level, to obtain the items needed to craft their gear, and that was the only way they could get new gear (outside of NM), then I think we would be better off without an AH. As it currently stands though, when you are level 15 and you need a lvl 16 weapon that requires lvl 30 BS and a lvl 45 GS item to craft it... as much as I hate to say it... you need an AH.
I am not saying that WE don't need one...
I am purely saying that MMO's would be better without one (if designed properly!)!
Buying gil happens because it requires so many crystals/shards to craft items. I made 1 mill in two days off of wind crystals (I wasn't even lvl 15 at the time).
I do give SE credit though... leve money drops made the game a lot better!!!! I think they help combat the RMT. I have bought gear off of someone just to see what the color looked like on my char :)
I think, until they are able to address the lag issue on NPCs, I think an AH would be retarded. I think YG and FFXIVPRO supplement the lack of an AH. The problem is finding the people that are selling the item (considering it takes me 5 minutes to spawn a group of retainers every time I move in the room). It really sucks when you look for someone for 45 minutes and you never find them.