The overlap of capabilities is between StackStorm and Salt -- the later has many orchestration capabilities. For event driven ops it can even be used alone. I don't want to say that one is better than the other, but this comparison does not surprise me at all.

As a friend (big Ansible fan otherwise) would say: "Ansible is just a glorified bash script; nothing more, nothing else". Without making it a bad product, Ansible is that one limited to CM only.

StackStorm developer here and I definitely am writing this as an engineer. We in fact use ansible for our own infra where we deploy a bunch of StackStorm nodes. Our CI CD pipeline, staging tests and packages promotion all are driven via StackStorm workflows. We also spin new environments on every merge commit to master (results in OS packages which are then deployed to a box) and have built sophisticated automation with StackStorm workflows. Every time I use Ansible, I cannot get over the fact that it is bash in Python. Our API driven approach, chatops, declarative when needed with workflows and ability to be imperative (write python code) for actions etc are things I really love. We are learning from all of the other tools ourselves but I also hope we are setting trends in workflow orchestration.