Seamed and seamless tubings are different processes (and there are a variety of both). Very good tubes can be made either way. Years ago, good tubing was only made seamless. No longer true. There are tubes made from materials which don't draw well but that can be rolled and welded to very high standards. (There are seamed tubes in places where high quality is far more important than anywhere on a bicycle. I'm willing to wager that seamed tubing has found its way into space flights and military aircraft.)
Ben