Down jacket construction confusion

Lots of companies use narrowly-spaced parallel lines (as opposed to a grid pattern) to contain the down in their lightweight jackets e.g. Patagonia Down Sweater, Hoody and Vest; Rab Microlight jacket and vest.

Will Rietveld at BPL recently reviewed the MH Nitrous, which uses narrow lines of down. His conclusion? The jacket dumps heat and breathes well because the lines create cold spots on the stitching and within 1/2" of the stitching because down. What gives? I want a jacket to be warm. If I want it to dump heat or be breathable during "active pursuits," I'll get a fleece.