Godot has a few elements going for it.

GUI Editor is not one I'd list.

Internal tooling stood up a GUI Editor clone within a few weeks that was targeted towards our specific use case. Their editor isn't uniquely ergonomic. In fact, for about 3 releases, one of the highest requested objects was multiple tabs at the same time. A rather standard feature in an editor and especially a modern code editor.

My argument isn't totally about individual devs making engines (though it is actually feasible on a Max plan), I'm imagining a very small team competitor that embraces AI-assisted PRs, internally and externally, along with vibecoding directly baked into the app itself (MCP or more direct claude code scripting language integration). That would be able to match or exceed the functionality in Godot, probably with more common and performant scripting languages (Rust + Luau for example).