: I've seen this done on this boat, but still wonder why the
: hull/deck aren't just glassed inside and out like most other
: boats are done?

No one said anything about not glassing the joint Bill. The rear deck joins at sharp angle to the hull. When you round over the sheer as drawn you could go through the core. The intent of the extra strip is purely to merely to provide more material at the sheer. Bjorn details using a regular size strip (right image, middle right) . Beefing up the strip turns it into a nice sheer clamp in the bow and stern where it's hard to reach. The cockpit definitely needs a few layers of glass on the inside.