Maybe I wasn't clear, but I wasn't talking about arbitraging. I'm talking about faking demand to hike prices and extend profit margin 10-fold. You can do this two ways - you can sell and buy cheaper, but then there's a risk that the price will stay low, so, you have more bitcoins, but less fiat. With this trick, you don't risk anything, and you make both more coins and more fiat.
Having Bitstamp and BTC-e copy the direction that Huobi takes without questioning makes them puppets in the hands of those who control Huobi and the likes. I think it's clear that Bitcoin market is predominantly amateur investors from the trigger-happy kind and the smart crooks can do with the market whatever they want with just a few hundred coins.
As recently the crypto wasn't profitable (the stock market performed way better) and people started to lose patience, some of those crooks had to do something to revive the market and keep doing what they've been doing so far. It's much easier to manipulate Bitcoin than the stock market, Forex, Gold, etc., so, those crooks didn't want to use their unique opportunity.
When you see "to the moon" everywhere, you know the game is back on, and many are gonna get taken advantage of pretty soon.