There are other reasons why it is hard to trade news. At times, we have surprise news which shock the market and nobody is able to anticipate. For a news trader, how would you catch something happening instantaneously but you have no access to much information to begin with. At times, you expect good data to be coming out and you are right with your prediction but price moves in the opposite direction instead, how would you react in such instances? This could be due to the fact that market has priced in good economic release and price has moved significantly prior to the release but market is expecting way better economic release, hence you may observe that price moves the other way.
Even with a Bloomberg terminal which gives you access to market news at an instant, it is still hard to catch price movement at that instance. In addition to that, you need to spend a lot of energy to be in front of your Bloomberg terminal and computer screen.