This is a bit like asking what the Marquis de Sade did that was so painful.
I don't even know where to begin explaining how frustrating Ansible is. Over time they've compounded one bad design decision on top of another, while never adding any actually useful functionality to be able to troubleshoot or iterate on the many random failures. They also don't provide guidance on how "if you use feature X, features a, b, c, d, and e will not work correctly". Finding a working example of core functionality, like an AWS inventory plugin, requires you to dig through all of the code and scour the internet and experiment for a day before you have a simple working configuration. The more features you use, the more fragile and shitty it becomes, to the point that nobody wants to actually change any roles or playbooks because deployments might stop working and it'll take you two days to figure out how to make them work again in Ansible's bass-ackwards design. And of course, it's Python, so you have to teach all your users how to use virtualenvs, freeze deps, and run it with Docker, or you'll constantly hear "it didn't run correctly for me".
It is easy to pick up and do easy tasks. Like installing a package on ubuntu and setup ufw. Then you throw in a few centos hosts and have to write if-else in yaml. Then u try to provision docker and end up with more if-else blocks to install the required python packages. Then you get to the part where you want to provision a database with presistent storage inside a docker container and just give up.
The two things that came into my mind when I first used Ansible was "bash" and "hudson/jenkins".
It seems like a tool which was written by an ops person (as in hacked together) for ops people (who don't mind stuff being hacked together), specifically for replacing manually distributed cryptic bash files. It's an improvement over that, for sure, but that's it.
Yes, if you freeze deps you can just install to the system paths in a Docker container. But most people who I've distributed Dockerized ansible git repos to don't read the README and don't try to run it in Docker, so they flail around trying to get it running without a venv or anything, until I finally convince them to just use the container (they're not familiar with containers either so it's almost as much of a slog).
I don't even know where to begin explaining how frustrating Ansible is. Over time they've compounded one bad design decision on top of another, while never adding any actually useful functionality to be able to troubleshoot or iterate on the many random failures. They also don't provide guidance on how "if you use feature X, features a, b, c, d, and e will not work correctly". Finding a working example of core functionality, like an AWS inventory plugin, requires you to dig through all of the code and scour the internet and experiment for a day before you have a simple working configuration. The more features you use, the more fragile and shitty it becomes, to the point that nobody wants to actually change any roles or playbooks because deployments might stop working and it'll take you two days to figure out how to make them work again in Ansible's bass-ackwards design. And of course, it's Python, so you have to teach all your users how to use virtualenvs, freeze deps, and run it with Docker, or you'll constantly hear "it didn't run correctly for me".