No, ABCS isn't simply a drag-and-drop development environment for citizen developers. Instead, it's an architecture for software developers to establish a drag-and-drop development environment for citizen developers! In other words, you can extend ABCS specifically for your business developers, with components that you define yourself... using Oracle JET. Or, more exactly, by creating Knockout components, which underpin the concepts used in Oracle JET.
Below, you see the "Hello World" scenario from the Knockout tutorials. It is part of an application created in ABCS by means of a "Custom Code" component. In the below, look on the left side in the palette, at the end, where you'll see "Custom Code":
Drag that into the canvas and then automatically the editors you see below open up, so that you can define your custom component:
And above you see the application deployed directly from ABCS. Really neat, the concept of "developing for the Cloud, in the Cloud".