One horrifying facts I've read about it is that ROS1 is completely non-realtime and non-deterministic, so much so that its ROSBAG data logs aren't time or sequence accurate. So you can collect the sensor inputs and simulate programmatic behavior, but it's acucrate only if you were lucky. And everyone has to either use it or devote massive amount of resource recreating it right way because there's just immense amount of useful packages available for ROS.