First of, Bevy isn't just an ECS implementation. It's a game engine designed around ECS. While the ECS part is its core, Bevy also provides rendering, resource management, physics, etc. One of its other tasks, a rather important one too, is system scheduling: once you register systems, Bevy is responsible for dispatching them each frame, at the appropriate time, while also avoid data races over global resources and components.
First of, Bevy isn't just an ECS implementation.
No one thought that or said that so I don't know what point you're trying to make.
If you go to the comments I replied it was someone saying bevy compiles slow and has excessive bloated binaries. Someone else replied that you get so much, like ecs. Then I said that ecs specifically is just a data structure and has no reason to bloat binaries to be 50MB for an empty program that does nothing.
You're replying about things no one was discussing.