I check the time when this thread posted repeatedly, finally I understand the meaning
In early January, Bitstamp lost 18,000 BTC, so they shut everything down for a couple days. When they went back online, they offered no trading fees for a while as an incentive to use their site again. No trading fees means you or a bot can take advantage of micro movements in the rates, hence more prone to a flood of micro transactions.
That's what prompted me to post the thread. Their fee structure is back again at this time. If you want no trading fees, look into
btchina.