You can't discredit JBL because of the era he was in. He still was a champion, and still has the longest reign in SD history. Before that he was a tag champion, then after that he had a solid US Title run. We can speculate that Shamrock would have had some sort of a title in a 2 world champion WWE but he didn't. He was a consummate mid carder, while JBL although not at the top of the card after he lost the title, continued to stay extremely relevant. Smackdown is the B show, but that B is very important, and being a World Champion on Smackdown means something. Just ask Taker, Edge, Hogan, Cena, Angle, Guerrero, Lesnar, HHH, Jericho, Hardy, Batista and others who all had the title on the "B" Show.