Mostly because the path to here was not a straight one :)

Our main Rails app does a bunch of things that can't run globally and it takes a long time to build while the customer facing app is a lightweight Rails app that consolidated several static and single page react apps into one less gross place.

That's actually the plan! The Ruby Graphql gem lets you resolve queries directly so the app can have an "edge" or "core" mode and make the right call (edge over HTTP, core direct to DB).