What's the point of Kelley Blue book if nobody follows it?

Is it common to get KBB value for a trade in? It seems like every car dealer wants to stress how inaccurate it is. Surprisingly, its always overvalued with them, never undervalued. And I think its funny how they stress that for trade-ins, but tout how much their cars are under KBB value. So what's the deal with KBB if no dealer ever follows it? Will they think I'm crazy if I ask for KBB value for my trade-in? Is there some gimmick or dealer strategy I'm not aware of?