They have to find a way to create enough control that chinabots don't buy every pocelkin or whatever the fuck for 1 divine and relist them for 5 divines every time some streamer posts a build. Same goes with even 1 alch shit like Shield of The Phoenix when some low life tech comes out and suddenly some dude named 1381841834810000 has every single one listed for 50 exalt 10 minutes ago. I'm sure there's a solution, but with the quick implementation of insta-item grabs you people are talking about, that's 100% what you would get right now.
A vendor holding your shit with premium tabs with hideout access granted by the owner on sale agreement would help 50% of the issues on the selling end, but you'd still have the 75% of the people who list shit and never sell it because they're lazy/price fixing/blind or whatever is going on.
If you don't think these economy whores wouldn't be CONSTANTLY fucking you on a mass scale if there wasn't the very, very slight friction of TFT to already do that, then I don't think you've got enough PoE hours yet. There are entire groups of people who live to do nothing but make currency. They don't even play the game after they've got their operation going. Don't even necessarily RMT. Just print money on mirror service and master crafts and weird shit and just pile it up. Meanwhile they vacuum up all the necessary bases and crafting components (which don't really exist outside of omen/greater essences right now) which fucks the mid level players.