[...] Real traders who want to sell will set their price below the wall. [...]
No, they don't.
Not all traders, no. But even if it's just some bots that want to make a quick sell, it does happen and it does drive the price down.
Let me try to understand your point of view better. Please answer this simple question:
A 100 BTC ask in the orderbook is:
[ ] Scary and you should put asks below it or sell at market immediately
[ ] A chance to do a big buy and take a big position without moving the market
[X] I'm absolutely not worried for myself as i'm only providing swaps, not trading.
Does every argument someone makes in a post have to come from worry about personal gain? I simply see something that doesn't make sense.