Your questions are valid, and you are correct that one size does not fit all. Frankly, the Google use case ('run lots and lots of as-yet-unwritten stuff on lots and lots of identicalish infrastructure') demands thie style of automation, but sacrifices other aspects of the final solution. This is a close use case to public cloud computing providers. However, in many cases (performance, security, etc.) it is not the most desirable model. This dichotomy is in my view one of the key points being overlooked by the dual champions of containerization, docker (non-profitable silly-valley hypetrain for LXC) and kubernetes (rethink of Google's internal container utilization seemingly in response to docker and EC2).