Crack initiation maybe could be from a nick or scratch that could have happened in that crash as you suggest. And since you brought it up, if I were Hope that would be my answer.
But a classic failure mode is cracking initiating from CNC milling grooves (Onza HO brakes anyone?). And there's plenty CNC action in the sculpted surface of that master reservoir and clamp. Mind you, all Thomson stems and posts are machined proving it can be done. But the devil is in the detail of alloys selection, matching the tooling spec and cutting parameters to it, and then a rigorous QA/QC regime checking the production. I'm afraid all it takes is a little burr on the tooling.
Common sense was never common
28h silver rear Suntour hub
32h Ritchey champagne WCS front hub