I completely disagree about less than one-tenth. The countries and locations that the qualifiers are held in have the most Pokémon fans. The games and TCG aren't even in most languages, only most of the most spoken languages, so there are many countries where holding qualifiers would be pointless.The world has close to 200 countries. And even then, players that live in forgotten areas of huge countries will always be left behind.
In other words, as long as it happens physically, you can't really call it a "world" championship with the "best players from the world", because not even one tenth of dedicated pokémon players have a chance to join.