"At the start of the Duel, 3 copies of Cyber Dragon are shuffled into your Deck. You cannot Special Summon or activate monster effect for the entire Duel, except Special Summon, Fusion Summon, or activating the effect of a "Cyber" monster. This skill cannot activate unless your Main Deck contains at least 10 different "Cyber" monsters.
Who the f will want his deck to have an extra of 3 "vanilla" cydras in his deck?? For what reason? Not to mention the drawback you describe. 1 cydra is usually more than enough. This would just be a never used skill.