How did the Reformation bring about a better understanding of the Trinity?

Joel Beeke explains in this video that the Reformation helped to point individuals to the Scripture and come to the understanding that there is only one Mediator between God and man. There are not individuals that we go to in place of Christ.

The Reformation gives us a Trinitarian theology in which our life can serve God. Samuel Rutherford exclaimed, “I know not which Divine Person I love the most–Father, Son, or Holy Ghost–but I know that I love each of them and need them all!”

1 Corinthians 8:6 (NKJV) – “[Y]et for us there is one God, the Father, of whom are all things, and we for Him; and one Lord Jesus Christ, through whom are all things, and through whom we live.”

And so the whole idea of, you know, going to God through saints and all kinds of mediators, no, no, there's one mediator between God and man, Christ Jesus, and so the Reformation bequeathed to us today a genuine Trinitarian theology so that we can say with Samuel Rutherford, I know not which divine person I love the most, but this I know. I love each of the three, Father, Son, and Holy Spirit, and I need them all. So bottom line, Reformation gives us a Trinitarian theology in which our whole life can serve God with head, heart and hands.