Here's why:
* Articuno is a Legendary Pokemon. Legendary Pokemon are typically rare and powerful creatures with unique capture methods. They are not usually obtained simply by accumulating badges.
* Articuno's capture method varies by game. In some games, you might find Articuno in a specific location after defeating the Elite Four. In others, you may need to complete a specific quest or event.
To find out how to get Articuno in a specific Pokemon game, you'll need to refer to a guide or walkthrough for that game.