Two reasons in my mind: (1) Supply and demand, and (2) flat out effectiveness. They are bad medicine for love-hungry toms.
When guys ask when is a good time to purchase land, the answer is always, "yesterday." They're not making any more land!
Same applies here. Lohman is no longer in existence. There is a finite number of Thunderdomes out there and they're not making any more. Every year, a few more of these calls fall prey to a pot call's worst nightmare: a fat guy in Mossy Oak smothers and busts it with his backside. And then there's one less Thunderdome in the world!