tobi did. and he had help. he had zetsu, who he thought was a full fledged akatsuki member, and he had karin, suigetsu, and juugoOrochimaru isnt cowardly at all, he just isnt blinded by a rediculous, undeserving sense of pride like most of the Uchiha, Oro knows where he stands, and he knows what he wants
AND HE DOESNT ****ING TRY TO ATTACK THE KAGE SUMMIT WITH LITTLE TO NO HELP, god damn sasuke, who convinced you that that was a "good" plan >_>