Of course we presume one knows. Why are you bringing up Old Testament people and Protestants? We are talking about Catholics and the obligations of Catholics. Do not bring those people in; their souls are between them and God.
Further, no one is claiming that God is limited by the Confessional, but he HAS bound mercy TO the Confessional, and the obligation to it as well. Perfect contrition forgives ONLY WITH THE INTENT TO CONFESS AT THE SOONEST OPPORTUNITY. So even then, the Confessional is NOT optional. If such a person does before making it to the Confessional, he is saved. But if he had the opportunity and did refused to take it, then his soul is in danger because he has not followed what God has ordained.
You’re the one who seems to see legalism where there is none. You’re the one who seems to think Confession makes things “harder” when in fact, it makes things much, much easier, because a person who is absolved KNOWS he is forgiven.