The same applies to a sinner. Teshuva is complex. A repentant person must admit his decades-spanning embarrassing, bankrupt approach and attitude. He realizes he toiled uselessly for decades to provide financial security for multiple generations that ignore and ridicule him. By day he will never admit his failure, but at night, on his bed, he will cry and realize he failed. He must verbalize failure in order to move past it. Torah tells the sinner: confess, verbalize your sins. Suppression causes it to fester and overwhelms the person. Confession liberates the confused sinner seeking to unburden himself.
Korban removes sin. Viduy sacrifice is spiritual, not physical, affliction associated with confession that shames the person, enhancing his repentance. Teshuva distances man from sin. However, confession effectively manifests afflictions of the soul as Korban, generating shame that enhances repentance, Lmaan Nechdal Mayoshek Yadaynu. Viduy facilitates acceptance of Teshuva like Ishim Vnichochim. We must sacrifice our pride and vanity through Viduy to attain the full repentance and atonement of Yom Kippur.