Volume traded and liquidity are not interchangeable terms. 
Volume traded is the only snap shot that an investor can make to liquidate their funds if needed. Yes, looking at the btc buy orders are another way
but as you know, those buy walls can and will be removed as people sell off only to put buy orders lower in the satoshi value hence lowering the true
liquidity value one can expect.
If there are 100 BTC worth of buy orders and 1 million KMD in sell orders, then there is liquidity ("how easily assets can be converted"); however, if the 2 sets don't meet in the middle, then there is low/no trade volume during a period of much liquidity.
Conversely, there can be a billion trades of the same 10 coins, during a period of low liquidity, that will produce a high "volume traded" amount (a perfect example of this is last Nov with UNIT coin when Craptopia used bots and microtrades to jack up the "volume" and the price by 3000x and the entire market [both buy and sell combined] was less than 0.5 BTC because they hadn't even allowed deposits yet).
I agree. Furthermore, these same 10 btc disappear when a sell off takes place. The bottom line is to have millions of traded volume when a project is on multiple exchanges.
I do agree that I or you could go on an exchange and buy our sells and sell our buys causing an artificial "liquidity" number. Point taken
