Godot isn't quite as ready for off-the-shelf usage in a high end game, mostly because of rendering performance. The architecture isn't performance-centric since the core team is focused on features and UX. It's fixable - everything is when the source is available - just a question of whether your project can justify the trade-offs and investment involved. To match what Unreal is doing right now essentially means writing a software renderer that executes on the GPU, along with various layers of streaming and caching to prepare assets for this pipeline; right now Godot is still aiming for lower-hanging fruit.

But since Godot is getting some serious backing these days, give it a few more years and it'll probably be a juggernaut in the space like Blender.