The order book is thin because there isn't much liquidity in either direction. You are comparing DASH to an extremely speculative coin with no official GUI client, where most all coins are sitting on an exchange ready to sell at a moments notice.
Compare it with other coins then, even some not-so-healthy ones like Peercoin. PPC has 1/5 the market cap but a very comparable bid side (so 5x ratio). And that's interesting because PPC has PoS rewards so there is an actual incentive to not keep coins on exchanges (though this doesn't really matter to bid side which is funded with BTC, USD, etc.). Still there is far better liquidity than Dash, relatively speaking.
Litecoin is probably comparable to the healthier non-r0ach-motel coins, but I couldn't get numbers because Poloniex (largest LTC/BTC pair) is down.
The r0ach motel effect is present in many coins to a degree, but Dash is much worse. It is on its way to becoming another Nxt, which by the way is another coin with a terrible initial distribution that made a lot of bogus claims about redistribution and was also promoted on the basis of allegedly amazing ongoing development. It didn't matter because for a cryptocurrency to succeed requires a lot of things, including a decent good and consistently
transparent distribution process and lack of any significant privileged parties that destroy the adoption incentive.
Just look at the last few months. DASH and XMR had a VERY similar run up, yet when it became time to take profits, only XMR crashed
That is exactly what you expect in a r0ach motel coin. Thank you for helping to make my case. There is no selling because the concentrated holders have nowhere to go. It would be futile to try to get out, since it would just crash the price. Dashholders check in but they never check out.
Also, check the DASH/XMR ratio. Still close to the low end of its trading range. So what you describe isn't really what happened.