Is there any reason to do Bilewater early?

If you go through Bilewater from the Sinner's Road entrance before finding Putrified Ducts, you hit a dead end after Groat. Also, you've just gone through the big maggot area without the anti-maggot item. Also I'm pretty sure you don't pick up any significant upgrades or progression unlocks, apart from the Apostate's Key.

So, why is the Sinner's Road entrance even there? Is there a theoretical run where going that way is useful? Not sure if I'm missing something or if it's just an extension of Bilewater's general sadism.