I can't attack what you don't have.
When you show me Ichigo defeating a Captain-class enemy with Bankai alone, or without outside help (And yes, other intelligence stopping his blood flow and giving him strength counts as outside help) I will agree with you that he can topple Senbonzakura alone. Until then...
He beat Zaraki with Shikai, actually.
He beat Byakuya with Bankai, although Hichigo interfered with that particular fight.
And the worse is, after Hichigo does his dirty work, Ichigo recovers conscience easily, by himself, like nothing ever happened, without any consequences. Hell, even in other manga the MC needs other's help to regain consciousness.