Having judges with similar training ensures fair comparisons. Wildly different palates would just confuse the scoring. The goal is to find the best BBQ, not the most varied opinions.
I saw the scoring sheets from the Memphis in May finals last year, and every judge was checking for the same basic stuff like smoke ring depth and tenderness. If one person loved crazy spicy rubs and another only wanted pure salt and pepper, the winner would just be whoever matched a random judge's lunch cravings. Trained palates keep the focus on cooking skill, not if someone happens to prefer extra sweet sauce. That consistency is what makes the trophy actually mean something.