Why would someone use this? Because they only want to deal with "one thing" in production. Dealing with multiple stacks is annoying. People show stuff like kubernetes as a way to handle multiple stacks. That stuff is also complicated.
There is still a huge opportunity for a methodology (accessible to non-operators) to get systems in production easily, where we wouldn't feel the need to force it all into these kinds of models.
Having said all of that, this is pretty fun looking!