Misunderstanding ECS is very common. Mostly because the name includes entity and component, so many people think that any architecture where you have an entity container with behavior defined in components is an ECS.
A lot of people also miss that in ECS, "System" is part of the "noun triple" and not a description of the first two nouns.
Put another way, there's a difference between an "Entity Component" architecture and an "Entity Component System" architecture. A lot of people read ECS as "A system made of entities and components" when it's actually "An architecture composed of Entities, Components, and the Systems that act on them".
Put another way, there's a difference between an "Entity Component" architecture and an "Entity Component System" architecture. A lot of people read ECS as "A system made of entities and components" when it's actually "An architecture composed of Entities, Components, and the Systems that act on them".