If one is negotiating a real estate deal, it certainly pays to understand the current real estate market, and even the broader economic climate as that affects property and resale values, demand for space, capacity to build, the ability to obtain loans, interest rates, and related issues.
More specifically, knowing a market enables the negotiator to arrive at more compelling standards for use when setting values. The uses of mutually acceptable standards is routinely recommended by proponents of principled negotiation. Once recognized, they give direction to a negotiation and support fair and doable deals.