Curves and disabled keyframes

[Gleb5C73]

Hello, I've just found out, that it's possible to change disabled parameteres using graph editor:

one selects one or multiple keyframes of the disabled parameter in timeline and then in graph editor one sees a curve that coresponds to the parameter. Then I can delete, move keyframes etc. (It's important to select keyframe dragging mouse, not just clicking on the keyframe)
Is it a bug or it's by design?

I've expected that disabled parameter can't be changed from UI.

[Gleb5C73]

Here a step by step example