Low Sale Price
Remember when your lowball bid was accepted? You jumped up and down in your rental's decrepit little kitchen, didn't you? But getting a steal sets up one more hurdle in actually closing the deal.
If there's anything a co-op board hates, it's something that could conceivably lower their own share values. And like a judicial ruling, a low selling price sets precedent. What's real estate worth? It's worth what someone will pay for it, and if that price is shown to be low, the value of all the units in the building drops.
What does a board member have to lose by disallowing lowball sales in economic tough times? Well, the poor seller can be stuck with a unit they can't move in current market conditions, and buyers can find themselves bullied into paying a price out of whack with the times (or bullied into going elsewhere). However, the board members have nothing to lose. If they, themselves, aren't trying to sell, why not put a stranglehold on sales until conditions improve and units can once again go for what shareholders see as fair rates?
Beware the lowball bid. Even if it's accepted, you might not be.