Think about the level of integration of Emacs and it's flexibility vs Eclipse/VSc/... the former is completely integrated and you can essentially modify any aspect at runtime with a simple sexp/config change. While the letter require to write and maintain plugins. The burden between programming and using in Emacs is substantially nonexistent, while you feel it on any modern software.
I do not know if it's clear seeing my bad English but I hope so. Think another example, Xerox model Alto&other Smalltalk machines, freedom it's not only the code but the way you use and customize your system, it's simplicity and flexibility. In FOSS we are all a bit devs, a bit admin, a bit users, a bit ..., while in proprietary world anything is rigid compartmentalized and "switch" between compartments it's not easy. The very same concept apply to containerization of software.
Example: I used to work at a place that, for a variety of reasons, needed to use custom builds of upstream Debian packages. So, we created our own Debian container base and rebuilt all the major Docker container "base" images (e.g. `openjdk`, `python`, `node`, `nginx`) with our own image as base. We had custom control all the way down to the OS level, and our orchestration solution (Kubernetes in our case, but a pile of shell scripts calling LXC directly works too).
I totally get being skeptical of {Docker|Kubernetes|Mesos|GKE|EKS|AKS}, but there's nothing inherently "un-free" about containers. They're a nice packaging primitive that happen to have some (useful, but not mission-critical) security features bundled in. So, your whole point kinda confuses me. That containers are standardized by OCI/LXC just makes them easier on your poor sysadmins to administer than 100 engineers' pet servers each running a different version of Emacs.