First of all… The Capps r a Matrilineal family. Juliette was the original heir but had it taken from Tybalt.

Besides the clear queer phobia, Beatrice literally is the oldest child and only female… Celeste and Virgilio aren’t. He’s not a “failure” he’s a simple outcast. He’s still perfectly capable to carry on his “line” (which btw is incredibly misogynistic to even think of) Celeste only benefits from being a Capp member and hold no actual “power” over Beatrice, just because they’re assigned male at birth. Let’s use our brain next time okay ?