If that were true, then so called "value investing" should also be priced out of the market due to efficiency.
The fact remains that trend following
does work. I know because I've done it. Many others on the forum have also done it. Many people have made absolute fortunes doing it, Darvas & Livermore for example. If you don't believe me, have a read of this white paper that was written by some fund managers on the topic:
http://www.trendfollowing.com/whitepaper/Does_trendfollowing_work_on_stocks.pdf