Honestly I disagree. The point was to keep them safe. They only knew of the Zetsu fodder army do realistically they had the advantage.
Even aside from that, the moment you lose them, you lose.the war. Keeping them at a location that was secure was a great option, because this prevents.the enemy from doing what they have to do to win. Instead they'd have to try and fine the target while your fodder army gets lambasted.
Had they known of Zetsu's power or Kabuto's Edo Spam....they likely would have placed them in battle.