react-pixi-fiber | Write PixiJS applications using React declarative style | Frontend Framework library

There are some interesting advantages when it comes to using a custom reconciler in React. As you see in the README.md file of react-pixi-fiber, it's totally possible to use ReactDOM to render the pixi elements instead of using the custom render from react-pixi-fiber.

Why create a custom renderer/reconciler then?

In this specific case the reason is that ReactDOM doesn't really deal with canvas elements. As you said though, that could have been achieved by a combination of custom hooks/components. If you read the why section of react-three-fiber you will see that by using their custom reconciler you can achieve two things, compared to custom components:

1. Everything from threejs will work here, because the support is built into the reconciler.
2. The performance is the same as when using threejs directly, because the reconciler has more control over what is rendered and when.

You can take a look here where there's an in depth explanation of the difference between render and reconcile and how the reconciler has fine grained access to: components lifecycles, decides the diffing and how elements are added/removed from the view (be in DOM, canvas, iOS etc).