There's also allegations about exchanges like Bitfinex where the owners/management trade on their own exchanges [0]. With insight on order book and people's stop prices there's an obvious conflict of interest there, as one can easily go stop hunting and manipulate prices. It's an unregulated market, and exchanges want to keep it that way (like how Binance's moving operations to Malta)
[0]: https://medium.com/@bitfinexed/wash-trading-bitcoin-part-ii-...
Bitfinex and Bitmex margin trading volume has increased significantly and for the exchange operators have access to
With those, it becomes insanely trivial to set some bait let the fish bite and simply drain the water or pump it back in on a whim because the order book is just a database and there's no accountability or auditing to keep the market exchanges honest.