DD's first underquilts also were not snugged against the hammock at the head end...there were big gaps between the quilt and the hammock.
One of the benefits of not being an innovator, and using a business model of running a close 2nd, is that you save R&D money by letting the innovators develop what you can produce cheaply. (Which is why a Burger King often goes up near a McDonalds a few months later.) The downfall of this strategy is that, since your engineers aren't solving the problems themselves, you also pass on the innovators' problems to your customers.
Sounds like their ridgeline advice is based on HH's early conventions rather than an understanding of the physics involved.