> Containers don't (generally) run in their own operating system
Right, but containerized application can't (ideally) talk to other applications on the same machine, that's how it's similar to a single-process OS with a single app running. Of course there are details like a single application may still contain multiple processes from OS standpoint, but the overall comparison stands.
> It's less similar to a bare-metal MS DOS application than it is a glorified chroot jail
These two cases are similar enough from containerized application standpoint (only OS services are different than those of MS DOS).
Right, but containerized application can't (ideally) talk to other applications on the same machine, that's how it's similar to a single-process OS with a single app running. Of course there are details like a single application may still contain multiple processes from OS standpoint, but the overall comparison stands.
> It's less similar to a bare-metal MS DOS application than it is a glorified chroot jail
These two cases are similar enough from containerized application standpoint (only OS services are different than those of MS DOS).