Yeah, I'm of the opinion that market flippers are the plague in online games. But game companies see nothing wrong with them, some even explicitly say they want to reward people spending time studying the market (specifically, FFXIV), so it's really just a difference of opinion in play style.
But it does spill over and make it hard for everyone who aren't really interested in making money. Those of us who have had enough of making money in the real world and just don't want to bother. We just want to do the quests, get quest rewards, and use that reward to buy stuff.
The existence of market players vastly accelerate inflation, compounding the RMT effect. People who RMT probably aren't bothering with playing the market, as they have that dollar to spend and they're really more interested in playing the combat and so on, which is the whole reason for RMT in the first place. So without the market flippers, RMT would still cause some inflation, but not rapid inflation, as RMT players get what they want and exit the market. Market flippers will stay in the market and continue to create false demand for items, thereby continue to drive up prices.
They often attribute inflation to RMT, but that's not really true when one talks about cosmetics in PSO2.
I don't think any game operator has ever solved the problem of "combat players" (i.e. those who don't want to bother playing the market) getting the short end of the stick when "market players" drive up the prices, making in-game quest rewards diminish vastly in value, so much so that they become pocket change. And then those market players turn around and laugh at people for not playing the market.
Admittedly, the problem is mostly mitigated for the top-end of the combat players who are able to get coveted loot and sell it. But anyone not inside that end-game gets screwed. The situation becomes more dire for new players as the server grows older.
Indeed I don't think any game operator has ever thought it a problem. They mostly think of it as diversity of play styles.
Imagine a PSO2 where cosmetics can only be traded once...