>>38282774They forget their own rule.
The Sinnoh Psychic Elite 4 Luson said you have to win in your home league to enter the Champion League, Ash can win any other league and build a hell of a Pokemilitary, come clean up with his various teams and challenge the Kanto E4 and Champion to obtain his goal.
Why do you think Ash never stayed in Kanto? If he did or challenges it again and wins it all he would be a Pokemon Master.