The implication is that nobody beat the Indigo Plateau Elite Four, or even gathered 8 gym badges, in a long time so the rank of champion was left vacant. Kukui, for example, in SM says he never made it past Lance in his trainer years.
Why Lance wasn't simply promoted to champion like he was two years after Blue is anyone's guess.
>>52961068This is new to me but doesn't make a whole lot of sense. If there was never any active champion period, why was there even a room between Lance and the Hall of Fame?