Phaser is just an all purpose 2D game engine, what kind of game you create doesn't matter. It gives you a lot of tools and functionality you're probably going to end up creating yourself if you used something that's just a rendering engine like Pixi.js instead. Phaser <=2 was built from Pixi.
OP didn't really build this from "scratch" in the strict sense, they used Three.js. This is kind of the 3D equivalent of Pixi.
