According to the author of Deuteronomy, God wanted Moses and the wise leaders to tell the people to follow all of God's rules. It's like when a parent tells their children to remember and do all the important things they were taught.
Deuteronomy 27:1: And Moses with the elders of Israel commanded the people, saying, Keep all the commandments which I command you this day.
These verses explain that Jesus came to fulfill the law, rather than just commandment-keeping as emphasized in Deuteronomy 27:1.
Matthew 5:17-18: Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.