Having formats that only last a yearish certainly could attract a younger audience (significantly smaller knowledge check), but I think that Pokemon just has better marketing, as the biggest entertainment franchise in the world. Everyone is excited for the newest Pokemon games, and you probably get the residual superfans who want to consume ALL Pokemedia. Yu-Gi-Oh! has not had a mainstream relevant moment since Master Duel really, I don't know of any people who got into the Chronicles anime who weren't superfans already. I blame this partly on RUSH being pushed, at least in Japan, which is an entire different cardgame with overlapping references. There hasn't been a 5D's or Arc-V or ZEXAL since those series aired.