Yep.

And there was a major push to sell the lots. Never sold one.

If these lots are so inexpensive and worthwhile, how come no builder has purchased for new homes? I know of two or three on Watertown Road. Those are underwater all year. What would you pay for a lot in a  true swamp that had six or so inches of water on it all year?

The lots in question are, for the most part, the most undesirable, worthless lots in Ocean Pines. They were so worthless the owners just stopped paying to keep them and ownership eventually went to OPA. 

All that said, OPA should sell those lots for any price, even to the point of giving them away. Why? Because, as you observe, now those lots pay zero assessment. In private hands, they would produce $1000 a year in assessments each.