Square-Enix, Yoshi-P and the other developers.
FF XIV's player economy is missing one of the most crucial elements that makes an auction-house based player economy stable; listing fees.
Without a list fee, players who are able to camp out the boards for 8+ hours a day are able to price gouge and monopolize the price of goods, making it impossible for any casual player to sell their wares for reasonable rates.
I don't want to single anyone out as doing something "wrong", because I believe they are entitled to game the system you designed for profits. But this isn't allowing other players to participate in the economy to raise money. That causes frustration, which means they are less likely to stick with the game.
A small number of players intentionally crashing markets to then buy up all the items and relist them at a much higher rate is not an imaginary thing. Players will outright admit this is what they are doing.
From the first page of this thread:
I have also done some experiments with items being sold at 1 gil. I've boughten them all up and then re-listed them at 50 gil each, and sure enough I sold all the stacks. But within 1 day that good was selling at 1 gil again. I dont know if it's bots or what, but it seems the market is endlessly getting crashed.
I have a level 50 Miner. Pretty much everything I mine is generally worthless at any given time of day, as there are people selling cobalt ore at 1-10 gil per 99 stack. This is true for a lot of the minable items on my server and it seems true for a lot of other gathering crafts, too.
Heck, even crafting materials items you can buy from NPCs, people are selling them for 1 gil.
You need to stop the ability for a small number of highly active players to camp the marketboards and continually undercut other more casual players. Simply adding a list price where the player must pay 5% of the rate just to list the item on the market board will address this issue. Players will no longer camp the boards and constantly undercut each other, or sell items for 1 gil. This is because they will end up not making any money at all.