Maybe it is a holdover from long ago. My 88 Myco is designed the same way, except the strake bunks are 4x6 cypress boards on edge, and difficult to align the boat evenly on. That's why the bunks are now angled along the hull under the chines, I'm sure. But, the keel bunks are 2x4's 12 feet long. Maybe, back when all bunks were one solid board, 12' was the longest reasonable length, an needed to be further up on the hull than placing at transom would allow. And that placement is still used today. Either that, or it's a vast conspiracy started by space aliens in cahoots with the government of Atlantis for purposses we don't yet know. Elvis is somehow involved in it;.