It was evidently common practice in ancient days, when the patriarchs (Abraham, Isaac and Jacob) were alive, for a father to give his family authority and wealth to his oldest son. That having been said, none of these 3 men actually did that. Abraham's eldest son was Ishmael, not Isaac. Isaac's eldest was Esau, not Jacob. Jacob's eldest was Ruben, not Judah nor Joseph.
Of course, Ishmael, Esau and Reuben all had lives that were stained in one way or another in ways that we think explains why they were passed over… well, sort of. Don't discount the value of Romans 9:10 - 13 in your meditations concerning this pattern. God's infinite, transcendent and eternal purposes are just that - infinite, transcendent and eternal. Neither you, nor I, nor any supposed scholar can sufficiently simplify that reality.
Anyway, Reuben slept with one of his dad's wives, so he was disinherited (Genesis 35:22). He most definitely got off to a bad start. Sad thing is: things didn't finish so well either. The end of the tribe was equal in debauchery to the exploits of their father. 1st Chronicles 5:26 tells us the conclusion of Ruben's family growth. Of course, Reuben's story is far too common (Deuteronomy 7:9-10).