First, if there is a limited number of houses available, and RMT are successful in buying and reselling at a higher price... they are actually doing a good thing.

It allows people who have the most gil to get the houses first instead of those first in line. I made my gil providing items for other people at a good price. I will probably have enough gil for 2 houses... I don't see why we have to introduce an entirely new currency just for houses. If we followed your logic we would have separate currencies for everything or we would just do away with all gil... that argument has already been made on these forums and I don't think we need to bring it back up.

Secondly, if there is not a shortage of houses available... then how will RMT make a profit buying and selling when someone can just buy from someone else?