Yes the article describes the Biblical Roots of the [Catholic] Liturgy, all of the elements of the Mass have a basis in Scripture. To the uninformed I am sure it seems confusing. There are many readily available sources from which to learn about it.
The obvious basis is the Old Testament Jewish priesthood, which Biblically speaking was done away with, with the crucifixion and resurrection of Jesus Christ. No further sacrifice is necessary, therefore no priesthood is required under the New Covenant. The righteous dead were led out of captivity in Sheol or Abraham’s Bosom by Jesus Christ also, so there is no need of the obvious model for Purgatory, either.
It seems odd to me, that the church models itself so after the Pharisees and the Sanhedrin to the point of actually claiming to be Israel, yet it seems embarrassed of the Book of Genesis and seems altogether too dismissive of the Bible it claims to have written. So, there is much that makes no sense to Christians outside of your church.