Why Docker/Containers has it's own networking concept(CNM/CNI) instead of using VM networking?

Question

I was recently reading an article on Container networking concept which explains the CNM(Container Network Model) and CNI(Container Network Interface) model.

Two questions come up:

1. Why we have such a networking design(CNM/CNI) for container?
2. Why we don't continue to use the VM networking schemes where we just connect different VMs to the host OVS while having a controller to update the flow table?