Disclaimer: I work at Google on Kubernetes

The problem containers are trying to solve is not isolation of environments (though, that's a tremendously good outcome).

The problem is how do you develop microservices that are self-contained, easily composable and inherently portable. It doesn't matter if you're running on Java 1.1 on AIX 3.0 or Node on Ubuntu 26, if I have a ball of computing providing a service in Dubai, and want to move it to Ireland to take advantage of computing space that just opened up, containers make that trivial (and about a million other scenarios).