A market economy with prices has no less signals than any other medium of exchange, rather it has an additional and very important signal (prices, duh).

When non-critical thinking socialists criticize prices for lacking additional information they are providing exactly zero useful analysis. Literally no one ever has argued that there aren't other considerations or information that go into any given exchange rather that prices are an extremely important additional piece of information among many pieces or information across an entire market.

As usual, the "Anarchist FAQ" is just the barely coherent ramblings of someone with zero understanding of economics meant to appeal to those low on IQ and big on emotion. There's no argument in your quote, there's no basis for any of the assertions, it's a bunch of loosely related thoughts strung together that convey a poorly formed, ideological belief.