A little background on that:
So, private confession was introduced a full seven centuries after Christ and His apostles. Ironically the Roman Church curses us if we dare assert the plain historical fact that secret confession to a priest was not observed from the beginning:
We don't need to reconciled to a religion and God never said it took years to do so. That's not the way Jesus taught or treated others.
Romans 5:10-11 For if while we were enemies we were reconciled to God by the death of his Son, much more, now that we are reconciled, shall we be saved by his life. More than that, we also rejoice in God through our Lord Jesus Christ, through whom we have now received reconciliation.
1 Corinthians 5:17-21 Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come. All this is from God, who through Christ reconciled us to himself and gave us the ministry of reconciliation; that is, in Christ God was reconciling the world to himself, not counting their trespasses against them, and entrusting to us the message of reconciliation.
Therefore, we are ambassadors for Christ, God making his appeal through us. We implore you on behalf of Christ, be reconciled to God. For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.
Colossians 1:9-23 And so, from the day we heard, we have not ceased to pray for you, asking that you may be filled with the knowledge of his will in all spiritual wisdom and understanding, so as to walk in a manner worthy of the Lord, fully pleasing to him: bearing fruit in every good work and increasing in the knowledge of God; being strengthened with all power, according to his glorious might, for all endurance and patience with joy; giving thanks to the Father, who has qualified you to share in the inheritance of the saints in light. He has delivered us from the domain of darkness and transferred us to the kingdom of his beloved Son, in whom we have redemption, the forgiveness of sins.
He is the image of the invisible God, the firstborn of all creation. For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authoritiesall things were created through him and for him. And he is before all things, and in him all things hold together. And he is the head of the body, the church. He is the beginning, the firstborn from the dead, that in everything he might be preeminent. For in him all the fullness of God was pleased to dwell, and through him to reconcile to himself all things, whether on earth or in heaven, making peace by the blood of his cross. And you, who once were alienated and hostile in mind, doing evil deeds, he has now reconciled in his body of flesh by his death, in order to present you holy and blameless and above reproach before him, if indeed you continue in the faith, stable and steadfast, not shifting from the hope of the gospel that you heard, which has been proclaimed in all creation under heaven, and of which I, Paul, became a minister.
And God made it simple. Far simpler than the Catholic church makes it.
The Catholic church teaches that to receive forgiveness, all kinds of actions need to be done in the form of penance, which is supposed to prove how sorry you are for your sin, as if God doesn't already know your heart.
God makes it this simple.
1 John 1:9 If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
That was then; this is now!
It COULDN'T have been; since there were no PRIESTS!
That is private confession, not confession itself. As the very quote you give states, in the early centuries it was done publicly and only for very grave sins. The sacrament existed all along, only how it was practiced changed. So what?