Ahm. Did you involve yourself in Eberron cosmology? I did never dm Eberron or play it pen and paper but i am a long time ddo online player and ddo is Eberron at its finest. It got a cross over route to FR in the game via the Demonweb, and to Greyhawk via portals, and a possibility to get to ravenloft via the mists, adding some classic DnD modules for all those settings.
What it does not do, and thats what counts is to refer to the Demonweb as 66th layer of the abyss.
And that is that. They intermingelled even some FR deities e.g. you can play a cleric of Amaunator.
But every reference to the planes uses the Eberron specific lore e.g. Fernia and Risia for Fire and Ice, Shavarath for everything devil and demon related etc etc.
No Abyss, no Nine Hells etc. And that is hat makes Eberron distinct. Everything got a twist there, even the normal great wheel assortation of planes or deities.
And on the term kitchen sink, FR has become one starting with 3e, it wasn't one in 2e.
Eberron is pulp, it is no vanilla fantasy setting so it is only a kitchen sink by its definition that everything D&D should have a place there - but with a twist.
From your posts i know you are not fond of polytheistic pantheons somehow, and i can understand you like Eberrons take on deities better and fear it might be diluted. But instead you should consider using Eberrons principles for other official campaigns in your homebrew to make it more to your liking.
