To me control is about articulation, in essence its what I call giving something a singular value meaning - I.e. for a user the control should feel ubiquitous with its manipulation. It’s not a bucket to store everything - it’s an access point that grants further manipulation. And this gets into a sticky situation because what is deemed manipulation vs control? - should controls have axis’, state, variance, analog notions of change or should that be on the manipulators of said control.
What deems something that is used by an animator and that can basically be anything given the right context - what does manipulation look like for an animator is more of a question. Bones could be animation controls if context is meaningful - Id argue anything can be an animation control if its promoted properly and that means attributes and state too.