You can have a non-ECS system without a giant inlined loop. If you look at an ECS for a typical 2D game what do you need? Components for: Sprites, Animation, So

You can have a non-ECS system without a giant inlined loop. If you look at an ECS for a typical 2D game what do you need? Components for: Sprites, Animation, Sound, Physics, Scripts, Pathfinding. All of which can be accomplished by function calls split up into separate source files. You can even begin with having everything inlined and pull the code out later once you've figured out what you want to do. ECS is overengineered abstraction to fit the set of all possible use cases instead of your specific use case. And if you write an engine that way you end up with an undebuggable mess of indirection for everything.