It's a "where are the bullet holes on the planes that survived" kind of problem. The thing that overwhelmingly kills game projects is overscoped design, which m

It's a "where are the bullet holes on the planes that survived" kind of problem. The thing that overwhelmingly kills game projects is overscoped design, which manifests into a need for very detailed, configurable entities with rich scripting functionality. So if you pursue scalability at the level of the entity system itself, as a thing you should invest substantial engineering resources to - you are effectively saying, "yeah, I have a team of 100 people to throw at the game's implementation and they are going to add literally every feature we brainstormed and also stuff we haven't". Because if you actually don't intend to do that, then you can instead adopt a pattern of prototyping it in whatever works well for authoring, followed by profiling and hardcoding a fast path as necessary. "Fast from the beginning" is just guessing about the bottlenecks. And that doesn't mean OOP is definitely good at the authoring task, either. It just happens to be good at kicking the can down the road and letting things work inconsistently, which may be correct in a prototype when you don't know if you're actually shipping that feature, and only poses an issue if you've tied the authoring to the runtime implementation in a deep fashion. Godot doesn't assume this; while it does have hierarchical relationships of objects, it has some boundary points with respect to reuse(scenes and scene instancing) that make the path of least resistance be to make separate authoring and runtime versions of entities, with one spawning the other.