[Schiendelman]

Sure. In this case, this started as a method with two parameters; each were validated internally before addition.

The validation was long running, as it required checking two other services to confirm both of the numbers were OK.

Because of issues calling those services, instead of two nasty synchronous calls, it turned into calling a microservice asynchronously and using a callback. Then that microservice was owned by the team that owned those two other services.

Don't underestimate the power of Conway's law.