It was a memorial for the Israelites, that no outsider who is not a descendant of Aaron should approach to burn incense before the Lord, that he might not become like Korah and his company – just as the Lord had spoken by the authority of Moses.
So if perfection had in fact been possible through the Levitical priesthood – for on that basis the people received the law – what further need would there have been for another priest to arise, said to be in the order of Melchizedek and not in Aaron’s order?