One thing that hasn't been mentioned is the practice of placing a large block order and then canceling it milliseconds later to take advantage of the price move

One thing that hasn't been mentioned is the practice of placing a large block order and then canceling it milliseconds later to take advantage of the price movement this causes. So placing a large order does not automatically create liquidity--it can create the momentary illusion of it. (This observation has to be pompously dismissed in gratuitously insulting terms--professional rational discourse will not suffice to explain indefensible practice. I must have touched a nerve.)