Here's why:
* Attack Declaration: In Yu-Gi-Oh!, you declare an attack with a single monster. You can't choose multiple monsters to attack with at once.
* Individual Attacks: Each monster can only attack once per turn, unless they have a specific effect that allows them to attack multiple times.
* Battle Phase Rules: During the Battle Phase, monsters fight one-on-one. If a monster's attack power is equal to or greater than the defending monster's defense power, the defending monster is destroyed.
However, there are ways to achieve a similar outcome:
* Link Summoning: Link Monsters have Link Arrows that point to specific zones on the field. You can link summon a monster using two or more monsters, potentially creating a monster with a high enough attack power to destroy the opponent's monster.
* Card Effects: Many cards have effects that let you combine the attack power of multiple monsters or boost a single monster's attack power, enabling you to destroy a larger opponent.
* Fusion Summoning: Fusion Monsters are created by combining multiple monsters from your field or hand, often resulting in a powerful monster with a high attack point.
Remember: While you can't directly add the attack points of multiple monsters together for a single attack, there are numerous strategies and card effects you can use to achieve a similar goal.