I consider it as a replacement for deploying applications as a virtual machine. That is, if I want to host compute and let anyone run any random program in a reproducible manner on my server, I could let them run it in docker and be done with it. So as am IT admin, I find this a useful alternative to letting people run arbitrary programs and add restrictions around it. I think this is more of an IT-OPS tool than something a developer would want to spend time with