>A bad abstraction would at least have had one fire in one place.

On the contrary: that's precisely what a bad abstraction would not offer.

Instead it would spread its assumptions to different parts of the system, as every caller, sub-service, etc. would have to change shape to fit in that abstraction's box, however unnatural it is (and we know it would be unnatural, because we already said it's a bad abstraction).

Abstraction is not the same as encapsulation.